Astronomers have used the Very Large Telescope (VLT) in the Atacama Desert region of Northern Chile to discover the strongest evidence yet that the famous star Betelgeuse has a companion star. That means after a century of investigation, scientists are closer than ever before to conclusively identifying Betelgeuse as a binary system composed of two stars, Betelgeuse A and Betelgeuse B.

Betelgeuse is a red colored star visible with the naked eye in the constellation of Orion and located around 650 light-years from Earth. Astronomers initially proposed the existence of another star orbiting Betelgeuse around 100 years ago in an attempt to explain the familiar star's strange dimming, which has been observed for over 1,000 years. While other teams have gathered evidence of the existence of Betelgeuse B, this new image is the clearest ever direct observation of the star. The scientists behind the discovery are thrilled.

"This is the conclusion of a century-long quest," team leader Miguel Montargès of the Observatoire de Paris, France, said in a statement. "We have shown that Betelgeuse is not single; it is accompanied by a faint stellar companion. I jumped from my chair when I saw the processed images."

The discovery of this new evidence of Betelgeuse B follows two papers published in 2024 that suggested this elusive stellar companion would be at its furthest from Betelgeuse A in December of that year. With that clue in hand, Montargès and colleagues set about hunting it.

"Honestly, I thought we did not have the sensitivity to detect Betelgeuse B as it was predicted," Montargès said. "Because it is more massive than predicted, we see it!"

Betelgeuse B had previously been theorized to be around the same mass as the sun, but these new observations reveal that this elusive star has instead around two to three times the mass of our star.

"The fact that we can still discover a nearby companion, more massive and brighter than the sun, around such a well-studied star is remarkable," Montargès added. "These are among the best moments in science: seeing something new, unexpected."

Capturing Betelegeuse B was only possible thanks to the VLT's SPHERE instrument, which features a coronagraph that blocks out the light of a planetary system's star. Combined with the advanced optics on the instrument, this allows scientists to measure the wavelength and polarity of light both coming directly from the star and being reflected off of any nearby planets. But that's not all SPHERE can do.

"It is remarkable to see how SPHERE and advanced post-processing techniques, originally developed to find exoplanets, also excel at detecting a companion around a massive, evolved star like Betelgeuse," team member Anthony Boccaletti, also an astronomer at the Observatoire de Paris, said.

There are still many questions to answer regarding Betelgeuse B. The team still needs to solidly confirm that what they have seen is actually a companion star, and they would also like to know how the presence of this star could shape the future of Betelgeuse A.

This red supergiant star nearing the end of its evolution gained notoriety a few years ago when its sudden and rapid brightening led to speculation it was about to suffer an explosive death.

"To be certain that the companion is really there, we still need to observe it in one year on the other side of the star, but there is very little space left for doubt," Montargès said. "The question is truly open whether this companion is going to have an impact on the evolution of the red supergiant."

The team's research was published on Tuesday (July 28) in the journal Astronomy & Astrophysics.

For the first time, scientists may have discovered a binary system—like the twin suns of the fictional planet Tatooine in "Star Wars"—where both stars exploded as supernovas, a new study finds.

Although Earth may orbit around a single star, more than half of all stars are in systems where two or more suns orbit each other. "When it comes to massive stars, the percentage in multiple systems are even higher," study lead author Miltiadis Michailidis, a postdoctoral fellow at Stanford University in California, told Space.com.

When massive stars burn all their fuel, they can die in giant explosions known as supernovas. These outbursts can briefly outshine all of the other suns in these stars' galaxies. They often leave behind expanding super-hot clouds of debris known as supernova remnants. Astronomers have detected about 300 such remnants in our galaxy to date.

Given how often massive stars are found in binary systems, "one can expect many pairs of massive stars where both will explode as supernovas," Michailidis noted. "However, this has never been observed, until now."

One reason supernova pairs may have escaped attention is that "if the stars are too close together when they exploded, the resulting supernova remnants may look like that from a single explosion," Michailidis explained. Another is that one star going supernova may propel its partner far enough away to hide the fact they were ever a duo, he added.

In the new study, Michailidis and his colleagues investigated a supernova remnant known as IC 443, located about 6,000 light-years from Earth in the constellation Gemini. IC 443 is also known as the Jellyfish Nebula for how it resembles a jellyfish.

IC 443 is one of the most extensively studied supernova remnants in the galaxy because of how shock waves from the supernova have collided with surrounding clouds of gas and dust to create a set of concentric bubble shells, "much like how a drop of water falling on a lake creates circular waves," Michailidis said. "It is very isolated from its surroundings, without many other objects nearby to complicate its very bright emissions."

The scientists analyzed one of IC 443's much dimmer, long-hidden neighbors, dubbed G189.6+3.3. The German-led ROSAT (Roentgen Satellite) mission first discovered G189.6+3.3 in 1994 via its faint X-ray emissions, and the Russian-German Spektrum Roentgen Gamma (SRG) space observatory later clearly detected shell-like structures within G189.6+3.3, suggesting that it was a supernova remnant.

In the new study, the researchers analyzed more than 16 years of data from NASA's Fermi Gamma-ray Space Telescope along with earlier X-ray, optical and radio measurements. They discovered signs that both IC 443 and G189.6+3.3 were both smashing into the same interstellar cloud of hydrogen, revealing they were close together in space, with the centers of their explosions about 30 to 50 light-years apart.

The researchers calculated that the chances of randomly encountering two unrelated supernova remnants at this distance from one another "was about one in 1,000," Michailidis said. "This suggests that our discovery is in fact the first known binary-system supernova pair."

The scientists estimated that G189.6+3.3 was older than IC 443, with the parent star of G189.6+3.3 exploding between 20,000 to 110,000 years ago, while IC 443 was created about 8,000 to 9,000 years ago. The original stars may have been 20 or more times the sun's mass.

These new findings can help shed light on how massive binary stars evolve, interact and die. For instance, further analysis of G189.6+3.3 and IC 443 can reveal how much of a kick the former gave the latter when it died, Michailidis said.

The scientists detailed their findings July 21 in the journal Nature Communications.

Reboots and remakes may be all the rage in Hollywood with mixed degrees of success (we don't talk about the Nightmare on Elm Street reboot ... ever), but they aren't so popular in other forms of art such as painting. However, a recent cosmic rework of one of art's most well-regarded pieces could be just as breathtaking as its original counterpart.

That's all thanks to the Dark Energy Camera (DECam), which has captured a vibrant view of the Corona Australis molecular cloud, that shows the star-forming region resembling a cosmic take on Vincent Van Gogh's iconic painting The Starry Night.

The Corona Australis Molecular Cloud measures around 16 light-years in diameter is located around 430 light-years from Earth, making it one of the closest star-birthing regions to our solar system. The molecular cloud and its dark lanes of gas and dust, the raw materials for star construction, are at the left of the DECam image.

Also prominent on the left of the image is the shining nebula NGC 6729, which is a reflection nebula of the Corona Australis Molecular Cloud. That means that it is a cloud of interstellar dust that is reflecting the light of the newborn stars embedded within this molecular cloud.

NGC 6729 is composed of different elements that can be seen on the left side of the image. This includes an orange cloud that is actually the binary star system R Coronae Australis. This binary consists of a pre-main-sequence star that has gathered mass but hasn't yet triggered the fusion of hydrogen to helium in its core, and its companion, a red dwarf star. These stars orbit each other every 43 to 47 years and are incredibly bright, with their light also reflecting from nearby reflection nebulas. This light also ionizes nearby gas, creating glowing regions called emission nebulae, also part of NGC 6729.

To the top-right of the image is the globular cluster NGC 6723, nicknamed the Chandelier Cluster. Located around 29,000 light-years from Earth, NGC 6723 is thought to contain some of the oldest stars in the Milky Way.

The Chandelier Cluster contains tens of thousands to millions of stars, which aren't all ancient; within the spherically shaped globular cluster are more than a smattering of younger stars.

Astronomers and astrophotographers of all levels will be more than familiar with the Corona Australis Molecular Cloud and the Chandelier Cluster and this region as a whole.

But just as it took the artistic vision of Van Gogh to transform the night sky into a stunning painting, it has taken the observing power of the DECam, mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile, to bring out the stunning beauty of this slice of the night sky.

Astronomers have spotted four dead star white dwarf stars playing a game of cosmic hide-and-seek, all four of which were hiding in the glares of red dwarf companion stars.

This marks the first detection of white dwarfs existing in double star systems in our cosmic backyard. The white dwarfs are all located within around 65 light-years of Earth, and one of them is number nine in the top 10 closest white dwarfs to the solar system.

White dwarfs are the type of stellar remnants left behind when stars around the size of the sun run out of fuel needed for nuclear fusion. This leads to their cores collapsing. The lack of fusion also means these stellar remnants cool and become dim. Thus, the light of much larger and brighter red dwarf stars is incredibly effective at hiding white dwarfs.

"Nearby isolated white dwarfs are usually easy to find, but we couldn't see these four stars directly in visible wavelengths because their red dwarf companions were drowning out their light," team leader Mairi O'Brien of the University of Warwick in the UK said in a statement. "It's a reminder that even in our own cosmic neighborhood, we can still find surprises if we look in the right way, at the right wavelengths."

Wobbles gave them away

Though astronomers have been diligently surveying our cosmic backyard for decades, white dwarfs are extremely good at remaining unseen. In fact, the only thing that gave these four hidden dead stars away? Curious "wobbles" caused in the motion of the stars they were hiding behind, like a hiding child causing a curtain to ripple.

The team followed up on these telltale clues by taking a closer look at these systems with NASA's long-serving Hubble Space Telescope. This investigation was conducted in ultraviolet light and using custom calibration to prevent flaring from the red dwarf companions from mimicking white dwarf signals.

This investigation not only revealed the four lurking white dwarfs, but also demonstrated that one of these systems, G 203-47, located just 25 light-years away, has some curious characteristics. Twenty-seven years elapsed between the initial radial wobble and the detection of this hidden dead star.

That isn't the weird thing, though. What is strange is that the red dwarf companion of this white dwarf only rotates once every 100 Earth days or so, yet it only takes about 15 days to orbit its dead star companion. This means that gravitational forces have failed to lock the red dwarf and white dwarf together, which is what happens in similar systems.

"What's fascinating is that G 203-47 shouldn't be rotating this slowly if it formed the same way as similar systems. This suggests that these binaries have had very different evolutionary histories," team member David Wilson, of the University of Colorado Boulder, said. "Some underwent violent, prolonged interactions early on that locked them tidally. Others, like G 203-47, experienced gentler, briefer encounters that left them in this unusual state."

The discovery of these white dwarfs helps researchers better understand the population numbers of the dead stars throughout the Milky Way. In fact, predictions would have suggested finding roughly four to five closely orbiting white dwarf-red dwarf pairs within around 65 light-years of our solar system, so finding four should instill a lot of confidence in our current theoretical models.

"Only about 30% of red dwarfs within 20 parsecs [65 light-years] have been systematically surveyed for hidden white dwarf companions," team member and University of Warwick researcher Pier-Emmanuel Tremblay said in the statement. "We think there could be as many as nine or 10 additional binary systems in our local stellar environment that we haven’t found yet.

"If we put more targeted effort into observing red dwarfs, perhaps we will find more surprises like this."

The team's research was published on Tues (July 14) in the journal Monthly Notices of the Royal Astronomical Society (MNRAS).

Astronomers have, for the first time, directly mapped the magnetic field surrounding an unusual "lighthouse" pulsar, revealing an invisible cosmic highway that channels particles blasted from the rapidly spinning stellar remnant.

Using NASA's Imaging X-ray Polarimetry Explorer (IXPE) mission, researchers measured the magnetic field around the pulsar PSR J1101−6101 — nicknamed the "Lighthouse" — and confirmed a long-standing prediction that its high-energy particles stream along magnetic field lines extending through the Milky Way. This discovery offers a rare look at how some of the universe's most extreme objects accelerate particles to nearly the speed of light, according to a statement from the space agency.

Pulsars are rapidly rotating neutron stars — the ultra-dense remnants left behind when massive stars explode as supernovas. Their powerful magnetic fields channel beams of radiation from their magnetic poles that sweep across space as the stars spin, much like the beam of a lighthouse.

PSR J1101−6101, which is located at the center of the Lighthouse Nebula, spins about 16 times every second and is traveling at supersonic speeds after receiving a powerful kick from the supernova that created it. As it tears through interstellar gas, it leaves behind a bright X-ray tail while producing a narrow filament that juts out almost perpendicular to its direction of travel. Astronomers had long suspected this unusual structure traced energetic electrons escaping along the Milky Way's magnetic field.

"We wanted to test that theory,"Jack Dinsmore, lead author of the study and undergraduate student at Stanford University, said in the statement. "The 'smoking gun' would come by measuring the polarization of the light, which indicates the magnetic field direction. If the magnetic field points along the filament, that confirms that the filament's particles are flowing along the field."

Unlike conventional X-ray telescopes, IXPE measures the polarization of X-rays — the preferred orientation of their electric fields — allowing scientists to reconstruct the geometry of otherwise invisible magnetic fields. Because the Lighthouse Nebula is relatively faint in X-rays, the researchers developed new analysis techniques to extract as much information as possible from the observations.

The team found that the magnetic field runs parallel to a remarkably long filament extending away from the pulsar, confirming that high-energy particles are streaming along magnetic field lines. But the observations also uncovered an unexpected twist: the field is far more orderly than scientists anticipated. The unusually strong polarization signal suggests the filament contains much less magnetic turbulence than current models predict, offering new insight into how fast-moving pulsars inject energetic particles into the surrounding galaxy.

"The striking divergence in magnetic field orientations observed between radio and X-ray wavelengths provides compelling evidence for the highly structured nature of these objects," Niccolò Bucciantini, co-author of the study from the Italian National Institute for Astrophysics, said in the statement. "This marks the first clear indication that particles of different energies occupy distinct regions within the system, hinting at the presence of multiple, and potentially very different, acceleration mechanisms at work."

Their findings were published July 9 in The Astrophysical Journal.

The universe is haunted by "cosmic ghosts" called neutrinos, and new research suggests they may be the "whispers" of stars that died in supernova explosions over the course of billions of years.

The discovery is an important step forward in our understanding of the life and death of stars and how they enrich their environments with metals, elements heavier than hydrogen and helium. It could also help better understand how black holes and neutron stars are born when massive stars die.

The second most common particles in the universe, neutrinos get their spooky nickname because they are chargeless and near-massless, so phantom-like that around 100 trillion neutrinos pass through you at nearly the speed of light every second, but over your entire life only one will interact with the atoms of your body, if you're lucky.

The newly suggested connection between neutrinos and a history of supernova blasts has emerged from the first detection of a flux of neutrinos called the Diffuse Supernova Neutrino Background (DSNB). It was detected by one of the world's largest neutrino detectors, the Super-Kamiokande, located 3,280 feet (1,000 meters) underground in Gifu Prefecture, Japan.

"Observing the world's first indication of the Diffuse Supernova Neutrino Background is a deeply meaningful achievement and has been a long-cherished goal since the beginning of the Super-Kamiokande project," Hiroyuki Sekiya of the University of Tokyo said in a statement.

Stars go out with a bang but continue with a whisper

Supernovas come in a range of types, but the ones this research concerns are so-called "core-collapse supernovas." These occur when stars much more massive than the sun reach the end of nucleosynthesis in their cores. When they are no longer able to fuse elements to create metals heavier than iron, the stars become unable to produce the outward energy that for millions of years has balanced them against the inward push of gravity.

Thus, with gravity the ultimate winner of this cosmic tug of war, the star's core collapses, sending violent shockwaves rippling outward into the outer stellar layers, which are ripped away. This leaves the core as a stellar remnant, either a neutron star or a black hole, initially surrounded by an expanding shell of supernova debris.

The energy from these events is carried away by particles of light (photons) spread across the electromagnetic spectrum, but also by neutrinos. Yet, despite the fact that supernovas have been erupting every second over the course of 13 billion years or so to produce the neutrinos that accumulate as the DSNB, this ghostly signal is still faint, a whisper rather than a shout.

To "hear" these cosmic whispers, the team behind this research analysed almost 14 years of data from Super-Kamiokande in the form of Cherenkov light generated when neutrinos interact with 50,000 tons of ultrapure water.

This revealed a signal of neutrinos in line with what would be expected from the DSNB. This signal still needs to be confirmed, but it is a strong indicator of the DSNB, the first humanity has ever had.

"We are already planning on incorporating ongoing observations at Super-Kamiokande together with its successor detector, Hyper-Kamiokande, to further improve sensitivity in future collaborative studies," said team member Yosuke Ashida,of Tohoku University.

The team's results were presented on June 25, 2026, at Neutrino 2026: XXXII International Conference on Neutrino Physics and Astrophysics, held at the University of California, Irvine, USA.

If the universe has one lesson for humanity, it is that everything ends. That includes stars, which too must die, albeit on timescales of billions of years. But new research suggests that when some stars die, they do not do so alone, potentially solving a long-standing mystery around a particular class of cosmic explosion called an interacting supernova.

When stars much more massive than the sun reach the ends of their lives, their cores collapse, sending shockwaves blasting out into their outer layers, triggering explosions called supernovas and leaving behind stellar remnants in the form of neutron stars or black holes. Interacting supernovas differ because the shockwave generated by these explosions crash into a pre-existing cocoon of material. The big mystery has always been: where does this cocoon of gas and dust come from?

Humanity is somewhat biased when it comes to stars; after all, the sun dominates our existence, and it is a solitary stellar body. But contrary to this, the majority of stars aren't so antisocial, existing in binary partnerships bound together by gravity. This new research suggests that these stars don't just live together; they can die together too. Understanding this dual existence could be key to solving the origins of dust shrouds in interacting supernovas.

"Our study suggests that many stars do not die alone," team member Ke-Jung Chen, of the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), said in a statement. "Their final appearance may be shaped by a long and intimate partnership with a companion star."

How somes stars become a drain

Before stars reach the ends of their lives, they enter a relatively short-duration red giant phase. This can see them swell out to hundreds or even thousands of times their original radius.

For a binary stellar pairing, this leads to a situation called "roche lobe overflow," which basically sees the swollen-out star spilling material onto its companion. However, not all of that material is captured by the companion star, escaping to form a vast cocoon around the binary stars.

When the evolved and swollen star reaches the end of its life and "goes nova," the shockwaves ripple forward and slam into this cocoon of matter at speeds of thousands of miles per second. The kinetic energy becomes light, creating a strange and intensely bright interacting supernova.

That leaves an obvious question, however. If stellar binaries are so common, and become even more common for stars massive enough to go supernova, why aren't interacting supernovas more common?

Turns out, just like with comedy, the secret is ... timing.

Chen and colleagues ran hundreds of computer simulations of mass transfer between binary stars and discovered that the key to generating an interacting supernova is when this mass transfer occurs late in the stars' lives.

If mass transfer occurs too early, say millions of years before the final supernova blast, the team found that the material spreads far away from the binary stars, dissipating the surrounding cocoon. For the cocoon to hang around for shockwaves to strike, mass transfer has to occur just a few thousand years before the final explosive death throes of one of the binary stars.

"We found that binary stars can prepare the stage for interacting supernovas with remarkable timing," team member Sung-Han Tsai of ASIAA said. "The companion star helps create a dense cocoon around the dying star just before the explosion, providing the fuel that powers these cosmic fireworks."

The team's research shows that there are many ways for stars to die, and these explosive fates are determined by the way they lived.

The team's research was published on June 30 in The Astrophysical Journal Letters.

Silent neutron stars at the center of supernova blast sites may actually be whispering softly, following the detection of faint radio emissions coming from one such object for the first time. The discovery raises the prospect that there could be many more pulsars in our galaxy than we thought.

When a massive star explodes as a supernova, the devastation leads to the star's core collapsing under its own gravity to form either a neutron star or a black hole. When a neutron star is formed, it is born spinning and its magnetic field is usually powerful enough to whip up charged particles and beam them away in a jet moving at close to the speed of light. This jet emits radio waves, and as the neutron star spins we see this radio jet flashing in our direction. This makes it seem like the neutron star is pulsing, hence we call it a pulsar.

Puzzlingly, not all neutron stars at the center of supernova remnants are pulsars. About a dozen discovered so far have been dead quiet in radio waves, and astronomers call these quiet neutron stars 'central compact objects', or CCOs. One possible explanation for CCOs is that their magnetic fields are too weak to produce detectable radio jets. For decades, astronomers have tuned into them, finding only radio silence  — until now.

A team led by Zhang Lei of the National Astronomical Observatories of the Chinese Academy of Sciences tuned into one particular CCO, named 1E 1207.4-5209 with the MeerKAT radio telescope in South Africa. They discovered that the CCO is pulsing with radio waves after all, but very faintly, once every 424 milliseconds. This matches the known spin period of the pulsar – it's a veritable whirling dervish.

Found at the center of a supernova found 10,000 light years away within our Milky Way galaxy, 1E 1207.4-5209 has been nicknamed the "Blue Eye Pulsar" by Li Di, a professor of astronomy at Tsinghua University in China. Its name is a virtue of the fact that when the faint radio emission is combined with X-ray images that show the neutron star shining brightly, it looks like a blue eye.

The Blue Eye Pulsar has an intriguing history. The supernova that formed it exploded over 4,100 years ago. In 2015, X-ray observations noted that the pulsar had experienced a 'spin glitch', which is a small increase in rotation of a neutron star probably caused by some kind of disruption or shifting of material within the neutron star's dense interior.

Lei's team propose that this glitch either strengthened or reoriented, or both, the magnetic field of the Blue Eye Pulsar sufficiently to trigger radio emissions, or at least make feeble radio waves that were already there detectable.

Following a glitch, a neutron star's rotation rate gradually slows back down to its original rate, at which point we might expect the Blue Eye Pulsar's radio emission to switch back off. Lei's team suggests that continued monitoring of the Blue Eye Pulsar could answer this question.

If that answer is what Lei's team think it to be, then it could mean that there is a large population of very feeble pulsars that remain undetected in the galaxy. Old pulsars, which persist long after the supernova remnant they were born in has dissipated, are also fairly quiet radio emitters because they are slowing their spin rate over time. However, it is possible that we have misidentified some of these pulsars as being old when they could in fact be relatively young but softly radio emitting.

The findings may also explain why some supernova remnants seem to be missing pulsars. Key among them is the expanding cloud of debris formed from the explosion of supernova 1987A in the Large Magellanic Cloud. Although astronomers are pretty sure there is a neutron star in the heart of the remnant based on indirect evidence, no pulsar radio emissions have yet been detected.

The detection of radio waves from the Blue Eye Pulsar was reported June 25 in Nature Astronomy.

Astronomers have used the James Webb Space Telescope (JWST) to observe an oddball gas giant exoplanet orbiting a dead star, a white dwarf, located some 80 light-years away. This "life after death" system gives scientists a portentous vision of what the solar system may look like in around 6 billion years after the sun has exhausted the hydrogen in its core, shed its outer layers, and left behind a smoldering white dwarf stellar remnant.

Prior to the final stages of that transformation, our star will have become a red giant, swelling out to many times its original radius, swallowing the inner rocky planets including Earth but leaving the outer planets  — although changing them irrevocably. Reflecting this, the white dwarf at the heart of this research is orbited by a Jupiter-sized exoplanet, designated WD 1856 b.

As WD 1856 b orbits its dead parent star, it crosses or "transits" the face of this white dwarf, known as WD 1856+534. By observing these transits with the JWST, the team was able to measure the mass and temperature of this Jupiter-like planet while also observing the composition of its atmosphere. To their surprise, they found WD 1856 b is hotter than expected. They also discovered how this planet came to have such an unusually tight orbit around its host white dwarf star.

"We're used to looking back in time when we use telescopes, but this is the first time we have been able to look forward to what might happen to the outer planets around the remnant of a sun-like star; it's like using a time machine to peer into the distant future of our solar system," team leader Ryan MacDonald from the University of St Andrews in Scotland said in a statement. "This is just the beginning of our exploration of planets orbiting dead stars with Webb, and the search for further planets orbiting white dwarfs is ongoing.

"Our results show that stellar death is not the end  — some planets experience a vibrant and lively future after the death of their star."

The team's research was published on Wednesday (July) in the journal Nature.

Survivor planet is a real oddball

The gas giant WD 1856 b was first discovered in 2020 by NASA's exoplanet-hunting spacecraft TESS (Transiting Exoplanet Survey Satellite) and the Spitzer Space Telescope. TESS detects exoplanets using the tiny dips in starlight they cause as they transit their host stars, blocking starlight.

This was the first intact planet ever discovered closely orbiting a white dwarf. What immediately stood out about WD 1856 b was how close its orbit is to its white dwarf host. The orbit is around 2% the size of Earth's orbit around the sun and takes just 1.4 Earth days to complete.

"The planet is quite the oddball. It's about the size of Jupiter, but the white dwarf it orbits is the size of Earth, so the planet is seven times larger than its star," MacDonald said.

The planet couldn't have always been in such a close orbit to its star. If it had, it would have been obliterated when the star transformed into a red giant before shedding its puffy outer layers and leaving behind a white dwarf.

"The big question is how WD 1856 b ended up where it is today, and there are two theories," team member Christopher O'Connor of Northwestern University said. "One is that the planet was swallowed by the host star as it was dying, and managed to survive on the inside. The other is that the migration took place due to the gravitational effect of other objects in the system. The white dwarf is part of a triple star system, and the outer companion stars could have influenced WD 1856 b's orbit."

The clue that allowed the team to differentiate between these migration mechanisms was the temperature of WD 1856 b, which at 260 degrees Fahrenheit (127 degrees Celsius) is about 240 degrees hotter than it would be if its only source of heat were the light from its white dwarf parent star.

With no energy available to warm the planet to these temperatures, the team reasoned that the temperature must be a residual effect of prior warming either from being engulfed by the red giant or during an inward migration. Using observations of the planet's mass of between four and 11 times that of Jupiter, the team was able to model how it would have cooled over time.

MacDonald and colleagues determined that WD 1856 b was likely heated up around 3 billion to 5.5 billion years ago. Its host star has been a white dwarf for longer than that, which means the exoplanet was safe during the star's destructive red giant phase, and moved into its tight orbit afterwards.

"As the planet moved inwards, its interactions with the strong gravity of the white dwarf will have caused it to warm up considerably, and it has been cooling ever since," O'Connor said.

The results indicate that Jupiter could move closer to the sun after the violent drama of its red giant phase and the destruction of the inner solar system. The findings also demonstrate the incredible observing power of the JWST and how the $10 billion space telescope is still discovering things no other instrument can.

"White dwarfs like WD 1856 are exceptionally dim compared to the planet-hosting stars we normally observe with the JWST," team member Victoria Boehm of Cornell University said.

"To make things even harder, the planet's transit only lasts 8 minutes, so it's very much if you blink you miss it! Capturing enough light to see WD 1856's spectrum, while also doing so quickly enough to not miss the transit, is something only Webb can do."

A huge, shining bauble of stars called Terzan 5 could be a clump of our galaxy's central bulge that hasn't been smoothed out into the mix, and has instead survived as a fossil relic leftover from the birth of the Milky Way galaxy.

"Terzan 5 may provide direct evidence that can help explain how bulges formed in galaxies throughout the universe," said Barbara Lanzoni of the University of Bologna in a statement. Lanzoni is a member of a team of astronomers, led by Bologna colleagues Giorgia Zullo and Francesco Ferraro, who tackled Terzan 5 with the James Webb Space Telescope (JWST).

Terzan 5 is a globular cluster — a huge sphere of stars with a total mass two million times greater than our sun's and a total luminosity 800,000 times greater. The problem is, Terzan 5 lies about 18,800 light-years away in the bulge of the Milky Way galaxy. This means dense lanes of intervening galactic dust block our view, significantly dimming Terzan 5's apparent brightness. That's why it wasn't discovered until 1968 by the Turkish–French–Armenian astronomer Agop Terzan.

Globular clusters tend to be ancient. They also tend to have formed all their stars in one giant burst. As such, all their stars should be the same age, 12 to 13 billion years old. Yet, a select few globular clusters show evidence of having more than one generation of stars. These include Omega Centauri, NGC 2808 and NGC 1783 in the Milky Way galaxy, as well as NGC 411 in the Small Magellanic Cloud and NGC 1696 in the Large Magellanic Cloud. Several explanations have been put forward, including the possibility that they are the core remnants of dwarf galaxies that have been stripped of most of their stars by gravitational tidal forces emanating from the Milky Way. Or perhaps these clusters were simply massive enough to retain some molecular gas for future stellar generations.

When the Hubble Space Telescope took a look at Terzan 5 in 2009 and then again in 2016, it found that it too was among the ranks of weird globular clusters with two generations of stars, dating back 12.5 and 4.7 billion years. However, because it is behind so much galactic dust, not even Hubble has the clearest of views.

The JWST, however, does. Its near-infrared vision can see through the dust.

"Webb's new near-infrared observations, cross-referenced with Hubble's archival observations, have given us a much clearer picture of the history of Terzan 5," said study leader Giorgia Zullo, who is a Ph.D. student at Bologna.

The JWST detected two further generations of stars, one generation born 3.8 billion years ago and another 2.5 billion years ago. Four generations of stars is hard to explain for any globular cluster, which is why the team think that Terzan 5 could be something more primordial: a leftover building block of the Milky Way's bulge that was never quite assimilated by our galaxy.

"For some reason, this peculiar clump of stars formed separately from the bulge and was not destroyed as the bulge itself formed," said Ferraro. "Terzan 5 is what we now call a bulge fossil fragment because it resembles the primordial clumps that contributed to the formation of the bulge."

Disk galaxies sport two main components: a relatively narrow disk formed from spiral arms, and a bulbous core called the bulge. Galactic bulges tend to be the oldest parts of galaxies, forming billions of years before the disks, at least in the Milky Way's case. The JWST is seeing this process occurring in the early universe, revealing clumpy, young galaxies, but given the great expanse of space and time that JWST is looking across, the observations of the building blocks that go into making these galaxies are still not totally clear. With Terzan 5, we could be looking at one of the building blocks of the Milky Way's bulge relatively close-up, and it could provide new insights into the birth of our galaxy.

Terzan 5 is probably not the only bulge fossil fragment either. As well as those other aforementioned globular clusters, some of which might be fossil fragments and others might be the cores of dwarf galaxies, the globular cluster Liller 1 close to the center of our galaxy shares many of Terzan 5's properties, including its high abundance of heavy elements produced by multiple generations of stars that have died either in supernova explosions.

The team are now looking to chase up another 40 or 50 globular clusters in the bulge to see if they could also be bulge fossil fragments, or whether they are just regular globular clusters.

The findings were presented at the 248th meeting of the American Astronomical Society in Pasadena, California which took place between June 14 and June 18. A paper describing the JWST observations has also been published in the journal Astronomy & Astrophysics.

Scientists have discovered that dying stars don't go down without a fight. New research suggests that when stars like the sun enter their red giant phase, they spit out blobs of plasma and receive a corresponding "kick" in the opposite direction.

Stars become red giants when the hydrogen in their cores is exhausted, and that core collapses. This results in the outer layers of the star where nuclear fusion is still occurring, puffing out and expanding the star's radius to as much as 100 times its original size. Those outer layers are eventually lost altogether, leaving behind a dense stellar remnant known as a white dwarf. The sun itself will undergo this transformation in around 5 billion years, swelling out to around the orbit of Mars and engulfing the inner rocky planets, including Earth.

California Institute of Technology researcher Jim Fuller calculated that before a star becomes a white dwarf, it will receive around 10,000 little kicks over the course of hundreds of thousands of years. The cause of these kicks is the ejection of blobs of plasma from the red giant stars.

"In this model, blobs of matter are chaotically being ejected from the surface of the bloated stars in an asymmetric fashion," Fuller said in a statement. "And every time that happens, the star gets a little kick in the opposite direction. Like Newton said, for every action there is an equal and opposite reaction."

The blobs of plasma will be chaotically ejected in random directions, but this will still result in an overall net push on the red giant, a phenomenon mathematicians call a "random walk." This is akin to randomly flipping a coin to decide whether to move north or south and still eventually finding yourself moved from your starting position.

Fuller determined that for a red giant, this random walk would see a movement in a random direction at a speed of around 2,200 mph (3,540 km/h). This may seem like a lot, but it pales in comparison to the kicks received by massive stars that explode as supernovas.

The lack of an explosion in the transformation of an average-sized star into a white dwarf makes these events less dramatic, but we have still seen evidence of this happening.

Caltech researcher Kareem El-Badry has previously discovered that widely separated binaries are less common in cases when one star has undergone the transformation into a white dwarf. One possible explanation is that repeated kicks during the red giant phase eventually break apart these loosely bound stellar pairs.

"If the orbital speed of the binaries is less than the kick speed, the wide binaries will become gravitationally unbound," Fuller said. Fuller's model also suggests something that astronomers are yet to see. He predicts that in some cases the kicks received by a red giant could send it pinballing toward a stellar companion, causing a massive explosion when the two collide.

Astronomers could now search the cosmos for such events, the discovery of which would help verify Fuller's model.

Fuller's results were presented at the 248th meeting of the American Astronomical Society in Pasadena. The study has been submitted to the Proceedings of the Astronomical Society of the Pacific.

Astronomers have a cosmic mystery on their hands, investigating a celestial crime scene to determine if a distant star has eaten a super-Earth exoplanet. The star may have had an accomplice — a failed star or "brown dwarf" companion — which may have steered the unfortunate planet toward its fiery doom.

The team charged with investigating this mystery first discovered hints of the crime when they found the star, TOI-5882, located around 1,300 light-years away, is surprisingly rich in the element lithium.

"You are what you eat, right?" team leader Brooke Kotten of the University of Michigan said in a statement. "We know that there's much more lithium in planetary material than there is in stars. So if a star eats a planet, it's going to take on a bunch of lithium."

So-called engulfment events such as this one occur very rapidly, on a timescale of a few days to a couple of weeks, which means catching stellar beings in the act of enjoying a planetary meal is extremely rare. Thus, astronomers have to act as cosmic crime scene investigators to reconstruct these events with the evidence at hand.

"That's what makes this field so exciting. You really are solving a mystery," Kotten said. "We can't just watch the crime happen, so we have to work with all the clues we're given to figure out whodunit."

One of the aims of these investigations is to discover the ways in which a star can devour a planet. One of the most common engulfment scenarios happens when a star runs out of hydrogen at its core at the end of its main sequence lifetime. This results in it swelling out to up to 100 times its original diameter, engulfing its attendant planets during its so-called red giant phase. This will occur in the solar system in around 5 billion years when the sun will puff out to around the orbit of Mars, swallowing the inner rocky planets, including our own.

However, Kotten and colleagues know this isn't what has happened in the TOI-5882 system, as this star hasn't yet become a red giant. Instead, the researchers think the sun-like star had assistance from its brown dwarf companion.

Companion brown dwarf of partner in crime?

Brown dwarfs get their slightly unfortunate nickname of "failed stars" because, despite forming from collapsing clouds of gas and dust, just like stars, they fail to grow to the masses needed to trigger the nuclear fusion of hydrogen to helium in their cores, the process that defines what a main-sequence star is. They're quite mysterious by existing in this sort of limbo between planet and star.

This particular brown dwarf has around 20 times the mass of Jupiter, or around 2% of the mass of the sun. That's not massive enough to trigger nuclear fusion, but is massive enough for it to have enough of a gravitational influence over planets orbiting TOI-5882. That means the team suspects this brown dwarf could have perturbed the orbit of this unfortunate planet enough to send it plummeting into its star.

This is something the scientists will need to investigate further. They may not have enough information yet to determine this planet's cause of death, but they do have some evidence that helps them identify the kind of world it would have been before it was obliterated. This comes from observations of the chemical composition and lithium content of 62 stars with similar ages and masses to TOI-5882.

"Lithium atoms delivered by planetary engulfment to a star are like sports fans arriving at a stadium," team member Seth Jacobson of Michigan State University said. "There may already be a few early arriving fans present, representing the initial amount of lithium in the stellar atmosphere, but they are quickly outnumbered."

From the lithium abundance they measured, the team has determined that this planet was a so-called super-Earth with a mass somewhere between two times that of our planet and the mass of the solar-system ice giant Neptune, which is around 18 times as massive as Earth.

"The fact that we can look at a star 1,300 light-years away and say with confidence, 'This star has more lithium than you would expect,' is a testament to both the precision of modern instrumentation and the hard interpretive work that goes into making sense of that signal," said Melinda Soares-Furtado, a senior author of the study and assistant professor at the University of Wisconsin. "And it's not like you have to cherry-pick the data to make it stand out. It's robust. No matter how you slice it, TOI-5882 is so enriched in lithium it shows up as being at least in the 97th percentile."

Soares-Furtado added that TOI-5882 is one of the few stars she has seen demonstrating evidence of planetary engulfment, although a few of the other stars in the control sample were enriched in lithium, albeit not to the extent of TOI-5882. That leaves another mystery for the team to solve, something that Soares-Furtado may well be quite content with.

"When I was growing up, I dreamed about becoming a private investigator," she said. "I think that explains a lot about where I ended up. I do feel like a detective."

The team's research was published on Monday (June 15) in The Astrophysical Journal.

Astronomers have discovered chemical differences between binary stars that indicate one is a cosmic cannibal that has devoured at least one planet.

Binary stars should have the same chemical composition because each star is formed from the same vast cloud of gas and dust; however earlier this year the team behind this new research discovered that the two stars of HD 81809, located around 101 light-years away, are chemically different. One of the stars, HD 81809B, has a much greater concentration of elements heavier than hydrogen and helium, which astronomers call "metals," at its surface than its binary partner HD 81809A.

This new research suggests that the reason for the metal enrichment of HD 81809B is that this star has consumed an exoplanet which was between 50 and 75 times the size of Earth.

"This is the first binary system to be found with this chemical difference, which is very unusual," team leader Nuno Moedas of the Technical University of Denmark told Space.com. "Binary systems are 'like siblings' in that they are born from the same molecular cloud, meaning they have the same chemical composition. As with siblings, some differences in element abundances can appear due to physical processes. However, these differences will be much smaller than those of HD 81809."

Moedas added that there are only two possible explanations for the differences between HD 81809B and HD 81809A.

"One is that the stars are not 'real siblings' and were born from different molecular clouds containing different elements," Moedas said. "The other explanation is that star HD 81809B suffered a more drastic event during its evolution, such as ingesting a planet, which could have changed its chemical composition."

There is a "smoking gun" piece of evidence that planetary engulfment is the correct explanation for the metal enrichment of HD 81809B, however.

"It could be very hard to distinguish the two scenarios, but the main evidence for a planet's engulfment is the high abundance of lithium in HD 81809B that is not normal," Moedas said. "Lithium is a very volatile element, and it is easily destroyed in stars, so we expect very low abundances of this element when observing stars. For the case of HD 81809B, the most viable explanation for the large presence of lithium is an ingestion of a planet."

The team isn't quite sure how HD 81809B came to feast on one of its planets, but Moedas suggests it could be the result of gravitational interactions between the binary stars disrupting the orbit of the unfortunate planet, resulting in it falling into one of its stars. The question also remains of how many planets HD 81809B has devoured.

"We can only estimate the amount of planetary material required, which we find to be 75 times the mass of Earth. It is possible that the star ingested three planets, each 25 times more massive than Earth," Moedas said. "The event happened a few million years ago, and there are physical processes in the star that will 'clean up' the evidence and try to make the star's chemical abundance similar to that before the event."

Because of the physical processes within HD 81809B, the team can't tell much more about the planet, or planets that were devoured. However, there is a possibility that this information may be recovered from a dusty disk of debris detected in this system.

"We still do not know the exact location, but if it is around the secondary star, it could be the remains of a planet falling into the star," Moedas said. "We could use this to understand the composition of the planet. However, we are far from being able to study this debris disk with the current instruments we have. We probably still need to revisit this system, as there is still a lot we don't know.

"There is a lot to discover."A pre-peer-reviewed version of the team's research appears on the paper repository site arXiv.

NASA's Chandra X-ray spacecraft has detected the supernova wreckage of a dead star near the supermassive black hole that sits at the heart of the Milky Way, around 26,000 light-years from Earth.

The team behind the discovery believes the star that died to create this wreckage erupted around 1,700 years ago. This represents the closest supernova debris found to our central supermassive black hole, Sagittarius A* (Sgr A*).

The supernova wreckage sits within a bubble of ionized hydrogen gas, which is a bright source of radio waves, and has been dubbed Sagittarius C (Sgr C). The wreckage was detected by Chandra and the XMM-Newton X-ray space telescope as a "blob" of X-rays. The shell of ejected material appears to be moving at a staggering 2 million miles per hour (3.2 million kilometers per hour).

Supernova wreckage like this is important for the chemical enrichment of galaxies, including the next generation of stars and planets.

That's because when massive stars like the progenitor star of this debris explode, the heavy elements they have forged from hydrogen and helium are jettisoned into their surroundings.

Eventually, these elements mix with surrounding clouds of interstellar gas and dust. Later, cool and dense regions in these molecular clouds collapse under their own gravity, forming new stars. The envelopes of material around these infant stars eventually form clumps that gather more and more mass to become planets.

There is still some ambiguity surrounding this wreckage, however. The team behind the observation didn't find increased amounts of the elements that would have been blasted out by the exploding star.

This could be because this debris has already mixed with the surrounding gas and dust. Alternatively, it could suggest this X-ray blob isn't the result of a supernova explosion at all, but rather comes from gas heated by the hot massive stars in this region of the Milky Way.

The team behind this research doesn't consider this explanation likely. That is because this X-ray emission is around ten times brighter than the typical emissions from clusters of hot massive young stars.

The team's research was published in The Astrophysical Journal.

One of the pleasures of stargazing is noticing and enjoying the various colors that stars display in dark skies.

Star colors are always interesting to observe, since they add so much to the character of the constellations. These hues offer direct visual evidence of how stellar temperatures vary. A good many of the luminaries of the summer season — such as brilliant Vega, which stands about halfway up in the east-northeast sky as darkness falls — are bluish white. Still, we can easily find other, contrasting colors there as well. Look at the reddish Antares and the yellowish-white Altair. And at the top of the line of this summer's retinue, brilliant orange Arcturus holds forth in solitary splendor high toward the south.

Even as you observe these stellar colors, do you notice that they're recognizable only for the brightest stars? This is due to the physiology of the eye, more specifically, the fact that the color sensors on the retina — the cones — are insensitive to faint light. Under dim illumination, the retinal rods take over. But their greater light sensitivity is offset by their color blindness. This is why faint stars tend to appear white to our eyes. However, if we look at them through a binocular or a telescope, their amplified brightness stimulates the cones, which detect their color.

Colors by contrast

One of the best ways to see star colors is by contrast. Let's return to Arcturus for a moment. The classic procedure for locating this star is to follow the arc of the Big Dipper's handle southeastward. Back in the 1950s, a very popular lecturer at New York's Hayden Planetarium was Henry M. Neely (1879-1963), who had a favorite ditty for locating Arcturus and another bright star of late spring/early summer: "Follow the arc to Arcturus and speed to Spica."

Spica shines with a distinct bluish tint. Move your eye rapidly back and forth between Arcturus and Spica to see the great difference in their respective orange and blue hues.

Another very effective procedure is to observe a double star with contrasting tints.

Probably the most colorful double star in the night sky can be found about halfway up in the eastern sky at 11:30 p.m. local daylight time: Albireo in the constellation of Cygnus the Swan, also known as the Northern Cross. Albireo supposedly marks the swan's beak.

A small telescope or even a pair of steadily held binoculars will readily split Albireo into two tiny points of light of beautiful contrasting colors: the brighter one a rich yellowish orange, the other a deep azure blue, both placed very close together. A stunning view will come with a telescope magnifying between 18x and 30x.

Stars hot and cool

Earlier, we referred to Antares as being reddish, which is how it's always described. But actually, that isn't correct. What we regard as "red" stars (which are catalogued as spectral class M) are really yellow-orange and approximately the same color as an old-fashioned incandescent light bulb. Both it and M stars have about the same 3,000 Kelvin color temperature.

Our eyes evolved to take advantage of the radiation emitted by the sun, which is an average star as far as temperature and color are concerned. Very hot and cool stars, on the other hand, are strongest in the ultraviolet and infrared ranges, respectively.

Starlight is similar to what physicists call black-body radiation — the electromagnetic waves given off by a body that emits and absorbs radiation 100% efficiently. (Anything that truly absorbed all the light falling on it would be black, hence the name). We know that the hotter a star, the more energy it emits at every wavelength — for very hot stars, the peak emissions are directed toward the shorter (bluer) wavelengths.

Simply put, the location of the peak emissions determines the star's color. We can break this all down into two rather simple laws that are immediate consequences of blackbody radiation.

For an object at a particular temperature, the total energy radiated at all wavelengths is given by the Stefan-Boltzmann law, after its two discoverers, Josef Stefan (1835-1893) and Ludwig Boltzmann (1844-1906). The Stefan-Boltzmann law states that the rate at which an object radiates heat is proportional to the fourth power of the absolute temperature, expressed in degrees Kelvin. Thus, if the temperature doubles, the energy output increases 16 times. If it triples, the output increases 81 times.

The second law is called Wien's law, named for Wilhelm Wien (1864-1928). It states that the wavelength of a star's peak output is inversely proportional to the temperature. If the temperature doubles, the peak wavelength is halved. Wien's law has a very colorful consequence, which can be demonstrated by the coils on an electric stove. As their temperature increases, we first feel infrared radiation, then see it glowing dull red, followed by bright red and still brighter orange. If it could continue heating without melting, the coils would turn yellow, white, then blue-white while becoming extremely brilliant — just like stars.

So, the color is determined by Wien's law, while the total radiation (both visible and invisible) is determined by the Stefan-Boltzmann law.

If you're looking for a telescope to get a closer look at the night sky our best telescopes for deep space guide may help. We also have a guide to astrophotography for beginners, which covers everything from equipment to shooting modes and more.

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, Sky and Telescope, The Old Farmer's Almanac and other publications.

A gorgeous new portrait of an ancient star cluster reveals an unexpected imperfection: a visible gap in the brightness of its stars.

The stunning image, taken by the European Space Agency’s (ESA) Euclid space telescope, captures NGC 6397 — one of the closest globular clusters to Earth. NGC 6397 is a glittering swarm of hundreds of thousands of stars packed tightly together, but when astronomers took a closer look, they discovered something unusual hidden within the sparkles.

A graph plotting the stars by their brightness and color revealed a conspicuous gap — a narrow region where certain stars should have appeared but didn't. The feature is so distinct that it stands out visibly in the data, appearing almost like a blemish in an otherwise smooth distribution of stars, according to a statement from the Space Telescope Science Institute (STScI).

The discovery emerged from observations collected by Euclid, which is primarily tasked with investigating dark matter and dark energy. Initially, the team was studying the motions of stars within the globular cluster using data from both Euclid and the Hubble Space Telescope. When analyzing the data from NGC 6397, the researchers weren't searching for missing stars. Instead, they stumbled across the feature while studying the cluster's stellar population.

"The discovery was serendipitous," Andrea Bellini, one of the research paper's primary authors from STScI, said in the statement. "We were not looking for the gap, but we found it."

The gap occurs among red dwarf stars, the most common type of star in the Milky Way. Researchers believe the visible void is linked to changes deep within the stars as they transition from having partially convective interiors to becoming fully convective. That shift slightly alters the stars' structure and luminosity, leaving relatively few stars at certain brightness levels.

The idea that stellar populations can contain small “missing” ranges of stars first emerged in 2018, when ESA’s Gaia mission revealed a subtle gap in the brightness distribution of hundreds of thousands of nearby stars. Plotted on a Hertzsprung–Russell (HR) diagram, the data suggested that even in large stellar populations, stars do not always fall into perfectly smooth patterns.

The new Euclid observations build on that idea by identifying a similar feature inside the globular cluster NGC 6397, which is a tightly packed, roughly spherical collection of stars bound together by gravity, often found in the outskirts of galaxies and containing some of the oldest known stars. Using a HR diagram, the team again mapped stars by their luminosity and color and discovered a narrow shortage of red dwarfs at specific brightness levels.

Because relatively few stars pass through this brief transitional stage in their evolution, there is a corresponding dip in their numbers at those luminosities. On the HR diagram, that shortage appears as a thin gap cutting through the otherwise continuous band of stars.

"Globular clusters are the ideal laboratories to study stellar evolution and stellar populations," Massimo Griggio, lead author of the study from STSc, said in the statement.

The precise brightness where the gap appears, along with the properties of the stars involved, helps astronomers estimate how far away the cluster is. NGC 6397, an ancient globular cluster about 13.4 billion years old, lies roughly 8,000 light-years away in the constellation Ara, the researchers said.

This marks the first time astronomers have identified the phenomenon in a globular cluster, providing a new opportunity to test models of stellar evolution using one of the galaxy's oldest and most densely populated stellar systems.

Their findings were published May 12 in the journal Astronomy & Astrophysics.

A triple star system in which the stars all eclipse one another from our vantage point is standing out as one of the best studied stellar trios; as the stars age, they could even merge.

The triple system, known as TIC 295741342, is 3,080 light-years from Earth and was found by NASA's TESS (Transiting Exoplanet Survey Satellite) mission. It features a binary system composed of two stars almost identical to the sun, orbited by a larger third star of 1.7 solar masses.

Triple star systems abound in the galaxy, but what makes TIC 295741342 more remarkable is that all three stars orbit each other in the same plane, and that plane is aligned edge-on to us.

TESS charts the light curves of stars, which is essentially a graph of brightness versus time. Typically, it is looking for the small dip in light as an exoplanet moves in front of, or transits, its star, but TESS also excels at witnessing stars in binary and triple systems also moving in front of each other — not just transiting, but eclipsing.

The light curve for TIC 295741342 is described by Brian Powell, who is an astronomer at NASA's Goddard Space Flight Center, as having a "head-and-shoulders" pattern, especially when inverted. TESS detects a dip in light as the stars of the binary at the heart of the TIC 295741342 eclipse one another. This dip is one of the "shoulders." Then, TESS detects another, deeper dip in light as the third, outermost star moves in front of the binary and eclipses both its stars, creating the "head."As the binary moves out from behind the third star while still eclipsing each other the light curve steps back up to the initial dip in light – the other "shoulder" — and finally back to full brightness when no stars are in eclipse.

Powell told Space.com that "very few known triple star systems are so near-perfectly coplanar as TIC 295741342, especially for being such a wide system."

Disk fragmentation

By coplanar, Powell means that all three stars orbit in the same plane, just as the planets of the solar system orbit in more or less the same ecliptic plane. Our planets are found in the same plane (or more specifically, within six degrees of it) because they formed from a disk of gas and dust that ringed the young sun. Powell suspects the stars of TIC 295741342 also formed from a disk, but one that fragmented.

"The protostellar disk broke into pieces to form stellar companions," said Powell.

Not all triple systems form this way. In many cases, the third star orbits at an angle to the central binary — but in those scenarios, the third star was gravitationally captured by the binary while they were all still in the close confines of their birth cluster.

Disk fragmentation is not a rare phenomenon, however. Hundreds of coplanar triple systems have been found, their numbers enhanced in particular by the discoveries made first by NASA's Kepler Space Telescope and now TESS. Yet few triple star systems are as well studied as TIC 295741342.

The two sun-like stars that make up its binary component have an orbital period of just 4.75 days. Separated by a distance of about 6.61 million miles (10.6 million kilometers); their masses were deduced from radial velocity measurements by the spectrograph on the 1.5-meter Tillinghast reflector at Whipple Observatory in Arizona. The third, outer star takes 412.8 days (1.13 years) to orbit the binary pair, at a distance of 157.7 million miles (253.7 million kilometers).

This is considerably wider than many other triple eclipsing stars that have been found, such as Lambda Tauri, which was identified in 1956 as the first known eclipsing triple where the outermost star has a 30.5-day period. Even closer is TIC 290061484, an eclipsing triple found by TESS in 2024, where the central binary has a period of 1.8 days and the outer star has a period of only 24.5 days.

Dangerous ground for planets

Could such triple systems harbor planets? There's an exclusion zone for planets in circumstellar orbits around binary stars in which a planet can get no closer than four times the binary period. In the case of the inner binary in TIC 295741342, that would result in a zone of instability out to an orbital period of 19 days, which is still pretty close to the binary stars. However, the presence of the outer third star at just a little further than the distance of Mars from the sun will curtail many possible planetary orbits further out from the binary. The third star could have its own planets, but again the binary would make any on larger orbits unstable.

However, in wide triple systems it's possible there could be stable planetary orbits, with some caveats.

"The orbit of a planet would have to be very wide," said Powell. "And it would be difficult to find."

One of the widest eclipsing triple systems is TIC 99013269, where the outer star is on a 604-day orbit at a distance of about 230 million miles (370 million kilometers) — less than half the distance of Jupiter from our sun.

It's fun to speculate about what inhabitants of any worlds or moons that exist around an outer star would experience during the eclipses. Picture a world with a habitable moon, tidally locked to its planet. For most of the time it will be in some form of daylight, whether from its star, which is the outermost star, or from the binary star a little further away, or even reflected light from the planet. However, at certain times a series of eclipses will line up — the outer star will eclipse the binary star, and the planet will eclipse the outer star as seen from the moon.

It would only be on these occasions when the planet-facing hemisphere of the moon would be in total darkness.

A future nova

While the coplanar nature of TIC 295741342 tells us about its beginnings, what we have learned about the stars thanks to them being coplanar is also telling us about how they will end.

The outer star in the TIC 295741342 system is beginning to age. It has moved off from the main sequence of hydrogen-burning sun-like stars and has turned into a red giant. It has already swollen to a diameter 10.6 times larger than our sun, and it will continue to expand. Eventually, it will grow so large and diffuse that the gravity of the binary star will begin to steal matter away from the red giant, which could lead to all manner of shenanigans.

Its diffuse outer layers may form a common envelope of stellar material encapsulating all three stars. This could cause the binary's orbit to become unstable and potentially merge. Then in the future, when the binary star component enters the red giant phase, long after the outer star has become a compact white dwarf, the mass transfer could begin again in the opposite direction, with matter falling onto the surface of the white dwarf. This would trigger explosive outbursts on the white dwarf, which would be seen across the galaxy as a nova eruption.

So its seems that the story of the three stars of TIC 295741342 has already been written, thanks to the careful observations including four years of radial velocity studies to calculate the mass of the planets, the observations of the eclipses by TESS, and the determination of the shape of the orbit of the outer star.

"The value in this system is the comprehensive data," said Powell. "This makes the system an excellent candidate for evolutionary studies."

The observations of TIC 295741342 are described in a paper currently on the pre-print archive arXiv.

The clashing magnetic fields of a white dwarf star and its neighboring red dwarf star are the source of signals from space that have remained a puzzle for over 20 years, radio astronomers in Australia have found.

The signals, or long-period radio transients, are a class of celestial radio emissions discovered in 2005. Most radio-producing objects release bursts that last for mere seconds or less, but long-period radio transients, about a dozen of which are known, produce radio waves in bursts lasting from minutes to over an hour.

Speculation had focused on highly magnetic pulsars called magnetars as the origin of these radio bursts, but now new research led by Kovi Rose of the University of Sydney, using the Australian SKA Pathfinder (ASKAP) radio telescope, has shown that symbiotic binaries are to blame for at least some long-period radio transients.

Symbiotic binaries feature a compact object — usually a white dwarf, which is the core remains of a sun-like star — stealing matter from a close companion star. This scenario often leads to a nova explosion when too much material accretes onto the surface of the white dwarf.

"Long-period radio transients have puzzled astronomers for years," said Rose, who is a postgrad student, in a statement. "Now we've been able to show that the source for one of these transients comes from a white dwarf actively pulling material from a companion star."

The system in question has been catalogued as ASKAP J1745-5051, and features a white dwarf that is about the diameter of Earth but a mass similar to that of our sun, accreting matter from a red dwarf star with a mass just a tenth of our sun's mass.

What makes ASKAP J1745-5051 stand out is that not only does it produce these long-period radio bursts, but it also produces blasts of X-rays.

"These emissions are all tied to the orbital motion of the system," said Rose. "But interestingly, the radio and X-ray signals don't peak at the same time, which tells us they're being produced in different regions of the system."

The X-rays are produced as matter spirals in from the red dwarf onto the white dwarf. As it gets closer to the white dwarf, gravity causes it to bunch up, friction increasing the temperature to hundreds of thousands, or even millions, of degrees, which is hot enough to emit X-rays. Exactly where it bunches depends on the relative positions of the white dwarf and red dwarf.

The origin of the radio waves is more complex. Both the white dwarf and the red dwarf have their own intrinsic magnetic fields. Their orbit around each other, which takes just 1.4 hours to complete, is not circular but strongly elliptical, meaning that at times the two objects are closer together than at other times. When they are close their magnetic fields clash, stripping charged particles from each other's surface. These charged particles then spiral around the magnetic-field lines and release a form of radio waves known as synchrotron radiation. The radio bursts last for the duration that the magnetic fields are in contact, every 1.4 hours.

While this explains ASKAP J1745-5051, it does not necessarily explain all long-period radio transients. For instance, only one other has been shown to produce X-rays. It is therefore possible that some other long-period radio transients have a different origin. However, Rose hopes that this new research will help distinguish between the different types.

"This system gives us a way to decode these signals," he said. "It could help us determine whether other long-period transients are more like pulsars or like white dwarf systems, acting like a stellar Rosetta Stone."

The findings were published on June 1 in the journal Nature Astronomy.

Some of the galaxy's most spectacular stellar nurseries resemble giant cosmic wagon wheels, with spoke-like structures that scientists say were sculpted by shockwaves from stellar explosions and powerful stellar winds.

Using powerful 3D simulations, researchers from Kyushu University and Nagoya University in Japan found that shockwaves racing through giant clouds of gas can carve out the spoke-like filaments often seen surrounding newborn stars. The findings could help explain the origin of so-called hub-filament systems — sprawling star-forming regions where long streams of gas radiate toward a dense central hub, creating a pattern that resembles the spokes of a wheel, according to a statement from Kyushu University.

"Stars are born inside molecular clouds — vast, cold clouds of gas that drift through space," Shingo Nozaki, lead author of the study, said in the statement. "But they only form in the coldest and densest parts of those stellar nurseries, where gas can collapse under its own gravity. In some of these star-forming regions, gas is organized into characteristic hub-and-spoke patterns known as Hub-Filament Systems (HFS)."

Astronomers have observed these structures throughout the Milky Way, but exactly how they form has remained an open question. The team used advanced 3D magnetohydrodynamic simulations to recreate the process, revealing that shockwaves propagating through giant molecular clouds can naturally generate the striking wheel-like architecture seen in some of the galaxy's most active stellar nurseries, according to the study.

Many stellar nurseries contain narrow filaments that funnel material inward toward crowded central regions where stars are actively forming. Understanding how those filaments emerge is key to understanding how gas accumulates and ultimately collapses into new stars.

For the study, the researchers built a virtual molecular cloud threaded with magnetic fields and ran the simulations on ATERUI III, a supercomputer dedicated to astronomical research. Gravity first was seen pulling the magnetic fields inward, creating an hourglass-shaped configuration. The team then blasted the cloud with a simulated interstellar shockwave similar to those generated by expanding supernova remnants or powerful winds from massive stars. The result was a remarkably realistic hub-filament system.

As the shockwave swept through the cloud, it encountered different parts of the curved magnetic field at varying angles, creating oblique shocks that amplified sections of the field and established preferred pathways for gas to flow. Over time, these channels funneled material into elongated filaments stretching toward a central hub, producing the spoke-like structure seen in telescope observations.

The simulations also tracked how matter moves through stellar cradles. Dense gas tends to flow along the filaments, accelerating as it approaches the hub, while lower-density material between the spokes remains comparatively still. The researchers say this behavior may help explain why only a small fraction of gas in molecular clouds ultimately forms stars, according to the statement.

Modeling the interplay between gravity, magnetic fields and shockwaves over millions of years, allows researchers to study processes that are otherwise difficult to observe directly. Future work will test a broader range of cloud structures and shockwave conditions, which could clarify why hub-filament systems vary across the Milky Way and offer new insight into the formation of massive stars and stellar clusters. The results also point to a broader cosmic cycle of destruction and creation, in which shockwaves from dying stars help shape the environments where new stars are born.

Their findings were published March 18 in The Astrophysical Journal Letters.

Astronomers have discovered the first signs that tiny red dwarf stars can devour their own planets.

Scientists had previously suspected that red dwarfs, which are considerably smaller and dimmer than the sun, could consume their own planetary systems — but evidence has been elusive. Until now, that is.

Researchers have used data from the Gaia-ESO Spectroscopic (GES) survey to discover red dwarfs with a high lithium content. This is unexpected, as red dwarfs shouldn't contain any lithium at all — unless they have gathered it by feasting on their home planets.

"Because these low-mass stars should have depleted all their lithium, the addition of even a trace from their forming planetary systems is readily seen — like throwing paint onto a completely blank canvas," team leader Robin Jeffries from Keele University said in a statement.

Though red dwarfs only possess between 8% and 60% of the mass of the sun, and are thus much cooler than our star, they are believed to harbor incredibly hot and violent interiors. This means any lithium they are born with should be rapidly burned through during the nuclear fusion processes that provide the star with energy to radiate.

This means stellar scientists have long been aware that discovering lithium in the atmospheres of these cool, dim stars would indicate they had consumed planets still rich in lithium from their initial creation. Indeed, this team found six red dwarfs in three different star clusters with vastly more lithium than would be expected.

The scientists analyzed their data further, determining that the red dwarf stars may have consumed the equivalent of three to ten Earths in planetary matter in total. This destructive process caused an influx of lithium into their atmospheres.

The fact that red dwarfs are the most common type of star in the Milky Way, accounting for around 75% of the stars in our galaxy, means this type of planetary engulfment may be extremely common.

Future research into these planet-eating red dwarfs could reveal at what stages of their existence they are more likely to consume their poor worlds, giving scientists a clearer picture of the early lives of planetary systems.

The team's research was published on Thursday (May 28) in the journal Monthly Notices of the Astronomical Society.

NASA's Fermi Gamma-ray spacecraft has observed a super-bright, supercharged supernova explosion that may have been powered up by a highly magnetic dead star, a type of neutron star called a magnetar. This magnetar would have actually been born in the supernova itself, forced into existence when the core of a star that was much more massive than the sun underwent gravitational collapse at the end of its life.

During these core-collapse supernovas, stellar cores with between one and two times the mass of the sun crush down to a radius of around 12 miles (20 kilometers) to create a neutron star, just like scientists say they see here. Not only does this rapid compression mean that neutron stars are made of material so dense that one teaspoon of it brought to Earth would weigh around 10 million tons (think 350 Statues of Liberty sitting on a teaspoon), but it also causes them to spin at rates as rapid as 700 times every second. The magnetic field lines of these dead stars are also forced together, intensifying the strength of neutron stars' magnetic fields, which makes magnetars the most powerful magnetic objects in the known universe.

"For nearly 20 years, astronomers have searched Fermi data for gamma-ray signals from thousands of supernovae, and while a few intriguing hints have been reported, none were definitive until now," team leader Fabio Acero of the University of Paris-Saclay said in a statement.

A superbright supernova

Over the last few decades, astronomers have observed around 400 core collapse supernovas, which, depending on the initial mass of the dying star involved, can also birth a black hole. Some of these stellar explosions are described as "superluminous" because they produce in excess of 10 times as much visible light as other core-collapse supernovas.

In 2024, scientists revealed they had successfully used Fermi to spot gamma-rays, the most energetic form of light, emitted from a supercharged supernova designated SN 2017egm. This supernova erupted around 440 million light-years away in the galaxy NGC 3191. Though that distance is so vast it took gamma-rays from the event 440 million years to reach Earth and Fermi, it is still one of the closest core-collapse supernovas to Earth ever seen.

"We searched for gamma rays from the six nearest superluminous supernovas seen during the first 16 years of Fermi's mission," Guillem Martí-Devesa, of the Institute of Space Sciences in Barcelona, Spain, said in the statement. "Only SN 2017egm shows evidence for gamma rays, confirming earlier hints that some supernovas can be as luminous in gamma rays as they are in visible light. This opens up a new window for studying these fascinating events."

Scientists are keen to discover what it is about superluminous supernovas that lets them pack such a powerful punch. One theory suggests this extra energy comes from the fact that these events birth a magnetar with magnetic fields 1,000 times stronger than those of "ordinary" neutron stars.

This team observed the optical and gamma-ray radiation emitted by SN 2017egm and compared this data to theoretical models of the flow of light and particles from a newborn magnetar. The models specifically reproduced how said particles would interact with the expanding shell of material shrugged off by the supernova's dying progenitor star. Of particular interest was a cloud of electrons and positrons in addition to their antimatter counterpart particles.

Scientists believe those particles were thrown out by the rapidly spinning newborn magnetar and call the cloud a magnetar wind nebula. The magnetar wind nebula is believed to boost the production and absorption of gamma-rays. One of the processes that would allow it to do this is the annihilation of particles and the release of energy as gamma-rays that occurs when a matter particle and its antimatter counterpart meet. These gamma-rays strike the outer shell of supernova debris and are turned into lower-energy optical light, explaining why these superluminous supernovas are so bright in visible light.

"About three months after the collapse, as the supernova debris expands and cools, the gamma rays can begin to leak out," Acero said. "This magnetar model best reproduces the supernova's luminosity and the arrival time of its gamma rays during the first months, but we see room for improvement at later times, when the visible light fades quite irregularly."

Acero and colleagues have a theory of what may be causing this gradual fade-out, suggesting it could be the result of debris ejected by the destroyed star hundreds of years prior to its supernova destruction falling back onto the magnetar.

The team also had one eye on the future, assessing how efficient the new ground-based gamma-ray observatory, the Cerenkov Telescope Array Observatory, will be at spotting events like SN 2017egm. They found that in 50 hours of observing time, the telescope array, located at the Paranal Observatory and on the island of La Palma, Spain, should be able to spot similar cosmic blasts up to a distance of around 500 million light-years.

That could help scientists finally understand these super-powerful supernovas.

"The magnetar central engine mechanism discussed in this paper builds upon a lot of observational and theoretical advances in magnetars over the last 20 years," team member Judy Racusin, at NASA's Goddard Space Flight Center in Greenbelt, Maryland, said. "Observing gamma rays from supernovae will give us a new way to explore their inner workings."

The team's results were published on Wednesday (May 20) in the journal Astronomy & Astrophysics.

Skywatchers across parts of the Pacific will see the moon pass in front of the bright star Regulus on May 23, temporarily blocking its light in a celestial event known as a lunar occultation. Elsewhere, viewers will watch the star pass extremely close to the lunar disk as the pair drift through the constellation Leo.

Why can't everyone see the moon occult Regulus?

The moon orbits Earth at an average distance of just 238,855 miles (384,400 kilometers), close enough for an effect called "parallax viewing" to occur, where an object appears to be in a subtly different position against its backdrop based on where you view it from. The parallax effect can cause the moon's position to vary by as much as 2 degrees depending on where you are on Earth, according to NASA.

Who will see the moon occult Regulus?

Stargazers in Fiji, Samoa, Tonga and a host of other Pacific island nations will see the shadowed side of the half-lit moon pass in front of Regulus during the early hours of May 23, blocking its light entirely, according to the astronomy guide In-The-Sky.

From Sydney, Australia, the blue-white light of Regulus will appear to graze the top of the lunar disk after sunset, before skirting around its sunlit side to set beneath the moon shortly before midnight.

U.S. viewers will get their best view of the cosmic duo overnight on May 22-23, as the moon advances towards Regulus through the late-spring sky. The moon and Regulus will be separated by roughly 1 degree, about the width of your little finger held at arm's length, by the time they set on the western horizon in the early hours of May 23, though the occultation itself won't be visible.

Don't forget, you can simulate exactly what the occultation will look like from your location by using a smartphone astronomy app, such as Stellarium or Sky Safari 7 Pro.

Editor's Note: If you capture an image of the moon with Regulus and want to share it with Space.com's readers, then please send your photo(s), comments, and your name and location to spacephotos@space.com.

NASA's Artemis 2 astronauts had quite the view on their "roadtrip" to the moon.

In this image, captured by the astronauts onboard the mission's Orion capsule "Integrity," you can see the swirling stars of space from the window as the crew journeyed from our home planet to the moon.

What is it?

This past April, four astronauts — commander Reid Wiseman, pilot Victor Glover and mission specialist Christina Koch of NASA and Canadian Space Agency mission specialist Jeremy Hansen — blasted off on a 10-day journey around the moon and back as part of NASA's Artemis 2 mission.

The quartet flew in an Orion capsule that they named "Integrity." This spacecraft came equipped with four windows, enough for each astronaut to have his or her own view. And you can see in this image that through these windows, the astronauts could watch the stars swirling by on their cosmic journey.

The crew successfully splashed down back on Earth in the Pacific Ocean on April 10. If all goes to plan, Artemis 2 will be followed by the Artemis 3 docking test in Earth orbit in 2027 before Artemis 4 lands humans on the moon in late 2028.

Why is it incredible?

On roadtrips on Earth, it's always fun to look out the window and watch the world pass you by. But on this journey, the view out the window was out of this world — literally.

This roadtrip snapshot also signifies something bigger: a big step forward in the journey back to the moon with Artemis. NASA's Artemis program aims to return humans to the lunar surface for the first time in over 50 years, since the agency's final Apollo mission in 1972.

But the plan isn't just to go back for a singular, celebratory landing on the lunar surface. Instead, NASA is aiming for a longer-term presence on the moon. Who knows? Future astronauts could soon be looking out their windows at the view on their way to stay at a moon base.

In its infancy, the universe had a bit of an identity crisis.

For the first few hundred million years, the vast cosmic gas between galaxies was primarily a chilly, dense affair. But then, it seemed to wake up, deciding to get all warm and fuzzy.

This strange shift in the cosmos’ early disposition is a crucial clue to how the very first galaxies burst into being, shaping everything we see today. The early universe, a mere whisper after the Big Bang, just a few hundred million years old — that's when the first stars and galaxies were starting to flicker on, like fairy lights across a cosmic dark.

The fuel for all this grand production: gigantic clouds of gas, mostly hydrogen. Astronomers have always suspected these baby galaxies were busy, but new glimpses from the James Webb Space Telescope are showing them to be even brighter and larger than our wildest dreams. They're like finding teenagers sitting in a kindergarten class, way ahead of their expected development.

This cosmic precociousness means our existing models of how galaxies form might need a serious tune-up. We thought we had a pretty good handle on how gas falls into dark matter halos, cools down, and then ignites into stars. But the JWST data suggests a much more aggressive, faster-paced star-making frenzy in those early days. The question becomes: How did these young galaxies manage such a booming business so quickly?

To untangle this mystery, Umberto Maio from the INAF-Italian National Institute of Astrophysics and the Institute for Fundamental Physics of the Universe, working with Céline Péroux at the European Southern Observatory, decided to dive into the virtual cosmos. They created incredibly detailed computer simulations, a sort of cosmic time machine called ColdSIM, to rewind the clock and watch how gas behaved in the first billion years after the Big Bang. Their goal was to make predictions about the early universe’s baryon budget — that's the accounting sheet for all the "normal" matter, the stuff stars and planets are made of, and where it ended up.

What they found was a universe in flux. Before a pivotal moment called the epoch of reionization — when the universe finally became transparent to ultraviolet light — the gas was indeed mostly cold. It was the perfect, dense environment for star formation. But as star formation really picked up, and that intense ultraviolet light started zipping around, things changed. The simulations showed that the gas quickly shifted, becoming dominated by a warm, less dense phase. It’s like the universe went from a quiet, cool morning to a bustling, sun-drenched afternoon, with all that energy from new stars and radiation heating things up.

This wasn't just a minor temperature change. It fundamentally altered the rhythm of galaxy evolution. The team's clever simulations traced the journey of various types of gas, carefully avoiding the usual shortcuts in models that can often lead to fuzzy answers. They found some eye-opening things about how these infant galaxies put themselves together.

For starters, the stellar return fraction was surprisingly low. This is the amount of material that stars eject back into the surrounding gas when they die, essentially recycling fuel for the next generation of stars. In the early universe, it seems, stars were less efficient at this recycling. Lower quantities of old stellar material returned to the gas, meaning that new stars largely formed from fresh, pristine gas constantly falling in from the cosmic web. It's a bit like a construction site that keeps getting new materials delivered rather than reusing much from demolished buildings.

But even with less recycling, these galaxies were burning through their gas at an astonishing rate. Maio and Péroux discovered that the depletion times — the time it would take for a galaxy to convert all its gas into stars at its current rate — were incredibly short. Much shorter than we see in galaxies today. This means that early galaxies were true star-forming machines, gobbling up gas and spitting out stars with a furious intensity. It paints a picture of baby galaxies throwing one heck of a tantrum, furiously making stars with every available bit of gas.

So, why does any of this matter? Because it rewrites a part of our cosmic origin story. Our initial predictions for these early galaxies, based on observations of later, more mature galaxies, simply weren't capturing this dynamic, rapidly evolving picture. It turns out that you can't just take what you know about middle-aged galaxies and apply it to their energetic youth. The physical processes, from gas dynamics to stellar feedback, are just too different when the universe itself is so young and compact.

Of course, this cosmic detective story is far from over. Numerical simulations are powerful, but they’re always battling with the sheer complexity of the universe. Modeling everything from the intricate, multi-phase structure of gas to the powerful winds blown out by massive stars and black holes is a huge challenge. There are still big uncertainties, like the exact initial mass function of stars (how many big stars versus small stars are born) and the precise amount of "metals" needed to kickstart cooling. Our models still have plenty of room to grow.

But the good news is, we’re armed with ever more powerful tools. The James Webb Space Telescope is out there, giving us sharper and sharper images of these distant, ancient galaxies. And coming down the pipeline are next-generation radio telescopes, like the Square Kilometer Array (SKA), which will let us peer even deeper into the cold gas reservoirs of these early galaxies. These new eyes on the sky will give us the crucial real-world data needed to test these new theoretical predictions, helping us refine our models and paint an even clearer picture of the universe's chaotic, yet beautiful, beginnings.

The journey to understand how the universe built itself, one galaxy at a time, is still unfolding before us.

Staring up at the night sky, you might envision a star flaring up, burning thousands of times brighter than usual. That's a cosmic explosion —  a supernova! Except it isn't. The star lives on.

These violent, non-fatal eruptions can make a star mimic a true supernova — leading to what we affectionately call "supernova impostors."

These are massive stars, prone to titanic temper tantrums, blasting out huge amounts of their own material. Astronomers call this "eruptive mass loss," and it's a stellar drama we're still trying to fully grasp.

Trying to understand these supernova impostors is like trying to weigh a raging volcano's output without getting too close. We know it's important, but measuring how much material these stars eject, and what makes them do it, is surprisingly hard.

Current ways of measuring mass loss from, say, infrared or radio observations, typically only show us what's happening right now. But these stars spit stuff out in fits and starts, not a steady stream. And when we try to average it all out across stellar populations, we lose the juicy details of individual star behavior.

For decades, astronomers have concocted intricate computer models to predict how stars live and die. These stellar evolution tracks are our cosmic crystal balls. But for truly gargantuan stars, the models often sputter out, unable to complete their lives in the simulation. One big sticking point? This very same eruptive mass loss.

Models include a way to describe it, imagining light pressure pushing material off the star, exceeding its stable luminosity limit – what scientists call super-Eddington conditions.

But the key to making this work is a free-floating efficiency parameter – a dial that controls the strength of the outburst. And nobody knew where to set it. It was a crucial, unconstrained value, holding back our understanding of how these cosmic giants evolve.

The struggle to accurately model these phenomena means that despite growing observational evidence of violent eruptions, the underlying physical mechanisms remain poorly understood.

But astronomers are a clever bunch. A team led by Shelley J. Cheng at the Center for Astrophysics | Harvard & Smithsonian, along with Charlie Conroy and Jared A. Goldberg, decided to tackle this problem head-on in a new study posted to arXiv.

Their idea? Instead of trying to measure every little burp from a single giant, they'd take a census of red supergiants across our nearby galactic neighbors – what we call the Local Group stellar populations. These are massive stars in their later stages, swollen and ruddy, shining bright across the cosmos. We know where they live. We know what they look like.

Wide-field surveys, like the PanSTARRS1 Medium-Deep Survey, have revolutionized our ability to spot these peculiar transients and luminous outbursts, helping us map out these red giants in distant galaxies. This observational power is crucial for gathering the data needed to calibrate eruptive mass loss.

The team used sophisticated MESA stellar evolution models, tweaking that mysterious efficiency parameter to see what happened. Then, they created mock stellar populations – basically, fake galaxies brimming with these modeled stars, sampling different initial masses and ages, just like real star-forming regions.

They then compared the predicted brightness distributions of these mock stars to actual observations of red supergiants in the Small Magellanic Cloud, the Large Magellanic Cloud, and the Andromeda galaxy (M31). It was like trying to match a blurry photo of a crowd to a lineup of suspects, carefully adjusting until the picture clicked.

What they found was that the efficiency parameter wasn’t just some random number. It showed a clear, positive trend with metallicity  —  the amount of heavy elements baked into a star.

More heavy elements, more violent eruptions. It's a bit like adding more baking soda to a volcano experiment – things get livelier.

With this calibrated eruptive mass loss, stars that start out truly massive – over about 20 times the sun's heft – are prevented from ever even becoming red supergiants in the models. Instead, these colossal stars shed so much material in their dramatic outbursts that they skip that red supergiant phase entirely, evolving down a different path.

But the universe, as always, holds more cards. This relationship between mass loss and metallicity looks solid, but we need to test it in more galaxies, not just our immediate neighbors, to confirm the trend is truly widespread. Future simulations will also need to dig into the nitty-gritty: Does metallicity affect what triggers an eruption, or just how much stuff escapes?

The saga of these spitting stars is far from over. Each new burst of observation, each refined model, peels back another layer, showing us just how dynamic and surprising the life of a star can be.

Here at Space.com, we love the night sky, rocket launches and sci-fi just as much as you do. Each month (from here on out) we want to celebrate that love by bringing you a collection of eclectic staff photos that show you a little of what we've been up to.

Expect launch photos, snaps of historic hardware destined for space, images of the night sky and, from time to time, photographic evidence of our entertainment editor Ian Stokes infiltrating Amazon's London office to sneak a peek at their May the 4th Star Wars offering … allegedly.

Don't forget! We love nothing more than seeing your discussions in the comments section under each article and, of course, featuring and enjoying your astrophotography, which you can share with us and the readers at spacephotos@space.com!

Photos from Space (.com)

We'll kick off with our spaceflight writer Josh Dinner, who took a road trip down to NASA's Kennedy Space Center in Florida to report first hand on the historic launch of the Artemis 2 mission to the far side of the moon!

"Witnessing SLS launch from the press site was more than just seeing the rocket liftoff  —  it was feeling it," Dinner told Space.com. "The shake and crackle of the solid boosters and legacy shuttle tech ripping through the sky is truly one to behold, and shooting Artemis 2 was an absolute experience. Whenever I photograph a launch, I always shoot at least a little underexposed. Accounting for the flame is important, especially when it comes to those blindingly bright solids."

"From farther away, you don't want to set your shutter too fast, but for my launchpad cameras, up close, that's where I'll plan for minimum exposure time. It makes your RAW images dark everywhere else, but that's all easily brought out in minor edits. I love getting to see the details of the flames as they explode from the rocket's engines.

"And with Artemis 2 I got extra lucky with some small water droplets that didn't quite dry off the lens as my cameras braved a rain storm the night before liftoff. They created some nice flares I think really add some uniqueness."

Managing editor Brett Tingley, meanwhile, set his sights further afield to photograph a stunning spiral galaxy shining 11.6 million light-years from Earth in the constellation Ursa Major.

"On March 28, 2026, I hiked out to a dark area in the Appalachian mountains to capture some deep sky objects," explained Tingley. "Bode's Nebula (Messier 81) was positioned perfectly overhead during the evening hours, allowing for a perfect long-exposure shot. Despite its name, Messier 81 is actually a galaxy - one of the brightest in the night sky."

"This was taken with a Celestron Origin Mk II using a nebula filter, enabling me to capture its spiral shape in great detail. It's incredible to be able to set up a smart telescope and watch images like this one develop in real time, putting deep space objects out in the cosmos right at our fingertips"

Space.com astronomy editor Monisha Ravisetti was lucky enough to spend a little time with the Nancy Grace Roman Space Telescope at NASA's Goddard Space Flight Center in Maryland earlier this month, ahead of its planned September 2026 launch.

"As a space journalist, it's tremendously routine for me to write about space telescopes," said Ravisetti. "I've pored over vast cosmic landscapes imaged by the tried and true Hubble Space Telescope, but what sticks out is this instrument launched before I was born. More times than I can count, I've tried to make sense of ancient black holes or glowing nebulas that sit millions of light-years away from me, but often, I owe these sights to the James Webb Space Telescope.

"Indeed, I've only seen the JWST in photos. My iPhone lock screen used to be a Euclid image, but again, I've never seen Euclid itself. These physical observatories have therefore remained in my imagination just like the universe they observe — places I'll never be able to explore."

"The Nancy Grace Roman Space Telescope is the first observatory headed beyond Earth that I got to see in person. It was a surprising experience. Did it look as grand as you'd expect something so pivotal to look? Not really, honestly. It was relatively compact, industrial and most importantly, comprehensible. It appeared as a piece of real, mechanical equipment.

"But while I looked on, I started to realize why it seemed profound to be this telescope's witness. It's surreal to remember a very reasonable object will eventually show us corners of our universe we haven't yet reasoned with. It's surreal to remember that these telescopes really aren't just intangible items in my imagination, and neither are those cosmic places I'll never explore."

Skywatching editor Daisy Dobrijevic captured a gorgeous view of the Triangulum Galaxy, using a smart telescope that cut through the light-polluted city sky to reveal fantastic detail on the deep sky object.

"I captured this view of the Triangulum Galaxy (M33) from my garden in Nottingham, U.K., using the Vaonis Vespera Pro," said Dobrijevic. "Despite working under Bortle 6 skies, I built up 3 hours of total exposure time across multiple nights, taking advantage of the Vespera Pro's multi-night observing mode — an invaluable feature when clouds inevitably roll in."

"I was genuinely surprised by just how much detail I could pull out in such a short amount of time, especially given the light pollution!"

Space.com editor-in-chief joined Dinner in Florida to witness the launch of Artemis 2 first hand, before heading out to Houston to report on the astronaut's progress as they broke the record for the most distant crewed spaceflight in human history, ahead of their safe return to Earth.

"I have waited my entire life to see astronauts launch to the moon," recalled Malik. "It was worth it. For just about my entire career, NASA has been trying to send astronauts back to the moon. First, it was Project Constellation and a goal of 2020. Then, maybe it was 2024. Then Constellation was cancelled and I instead watched dozens of space shuttle and rocket launches stay in low-Earth orbit. Even Artemis 1 in 2024, I missed. It was scrubbed several times (I saw them all) and when it finally did fly, I couldn't be there."

"But a month ago, Artemis 2 was something else. I've seen the largest rocket on Earth — SpaceX's Starship — launch (and explode) and that was loud. But watching four astronauts launch on NASA's most powerful rocket since the Saturn V hits different. First, it was SO LOUD. Much louder than the Starship launch because we were just 3 miles away (about 2 miles closer). You felt it in your bones and it drowned out all sound. But also because there were PEOPLE on this one. Four astronauts that I have spoken with personally at one time or another. Then they went to the moon.

And for the first time in my 49 years, more than half of that as a space reporter, I feel like a new space age is finally beginning, one in which astronauts finally reach the moon to stay, then Mars, and then who knows where else? (I vote for Titan and Venus, but that's just me.)"

Our senior producer/video wizard Steve Spaleta chose to reminisce over a collection of legendary aircraft — and the creation of a legendary photo.

"After covering the unveiling of Virgin Galactic’s Spaceship Unity at the Mojave Air and Space Port in February 2016, Dave Brody (Space.com’s former exec. producer) and I visited the Joe Davies Heritage Airpark in Palmdale. The photo here shows a retired Shuttle Carrier Aircraft, a Boeing 747-100SR—one of only two ever used to ferry space shuttles.

"The outdoor aerospace museum, free to the public, also features a Lockheed JetStar used by NASA, along with several military aircraft, including a B-52 Stratofortress. Dave Brody snapped the image and joked, “add a Rick or an Alembic, and that’s an album cover.”

Harry Bennett, our e-commerce staff writer and overall photography enthusiast snapped a stunning view of Vega shining in the constellation Lyra.

"Vega shines a beautiful white-blue with four prominent diffraction spikes, giving it an angelic presence amongst a vast star field, " said Bennett. "It is the fifth brightest star in the night sky and the second brightest in the northern hemisphere. I took this shot using the enhanced vision mode on the Unistellar Odyssey Pro, which stacks four-second exposures continuously until you stop it."

"I have a soft spot for it because it is the first smart telescope I ever used and it gave me the ability to capture mind-blowing images of night sky objects even from a city center. It is fully automatic and can orient itself, find a target and start imaging all from a few presses on your smartphone. People can be swept up in smart telescopes’ ability to capture amazing detail on deep-sky objects like galaxies but forget that imaging individual stars can really make you feel magical."

Entertainment editor Ian Stokes went off campus to take a look at Amazon's office in London in disguise as a scout trooper. At least we think it's Ian?

"I channelled my inner Bothan and managed to infiltrate the Amazon office in London and while they didn’t have the droids I was looking for, they did have a bunch of Star Wars merch on display ahead of the May the Fourth festivities. They had a bunch of cool lightsabers, figurines, and helmets for staff and visitors to check out, including the snazzy scout trooper helmet that I’m sporting here.

"Sadly I was escorted from the premises when I tried to add myself to the cast list for the new Stargate show they’re working on."

Editor's Note: If you would like to share your photography with Space.com's staff and readers, then please send your photo(s), comments, and your name and location to spacephotos@space.com.

Astrophotographer Mark Germani captured a phenomenal view of the Pleiades open star cluster surrounded by glowing blue nebulas 445 light-years from Earth in the constellation Taurus.

Germani's deep-space photo reveals dozens of stars from the Pleiades, a cluster of over 1,000 blue-white stars, including its seven brightest members Alcyone, Asterope, Merope, Celaeno, Electra, Maia and Taygete, from which it gets its nickname of the "Seven Sisters".

The bright stars are surrounded by vast interstellar clouds of dust and gas known as reflection nebulas, which preferentially reflect the blue light of nearby stars, according to NASA. Astronomers believe the dust is not material left over from the cluster's formation, but a cloud the Pleiades is simply moving through.

Germani spent over 18 hours imaging the Pleiades from his viewpoint in Vancouver, Canada, using an Askar SQA55 quintuplet refractor telescope and ZWO astronomy camera fitted with a filter designed to block wavelengths of ultraviolet and infrared light.

"I have had some difficulty with M45 in the past, so I decided to take a different approach with this image, ditching my light pollution filter and swapping in a UV/IR-cut filter in an effort for better colour and more faint dusty detail," Germani told Space.com in an email. "I managed 7 nights in January and snuck in a few extra hours on a night in February."

After soaring high in the winter sky, it's becoming increasingly difficult to spot the Pleiades. Currently, it can be found shining low on the western horizon in the hours following sunset in late April, but it sets less than two hours after the sun.

In its place rises a host of spring constellations filled with galaxies and other deep sky wonders! Be sure to check out our roundups of the best telescopes and binoculars if you want to explore the night sky for yourself, along with our picks of the best cameras and lenses for astrophotography.

Editor's Note: If you would like to share your night sky photos with Space.com's readers, then please send your images along with your comments, name and location to spacephotos@space.com.

Astronomers have found the boundary of star formation in the Milky Way's spiral disk — and it's not as far out from the center of our galaxy as you might imagine.

The Milky Way is at least 100,000 light-years across, but the new results suggest that the galaxy's star formation takes place within a region that extends to a radius of 40,000 light-years from the galactic center.

"The extent of the Milky Way's star-forming disk has long been an open question in galactic archaeology," said the study's lead author, Karl Fiteni of the University of Insubria in Italy, in a statement. Fiteni carried out this work while a PhD student at the University of Malta, under the supervision of Joseph Caruana (University of Malta) and Victor Debattista (University of Lancashire). "By mapping how stellar ages change across the disk, we now have a clear, quantitative answer."

Fiteni's international team focused on 100,000 luminous giant stars spread across the Milky Way's spiral disk, obtaining spectroscopic data describing their temperatures and ages from the LAMOST (Large Sky Area Multi-Object Fiber Spectroscopic Telescope) telescope in China and the Apache Point Observatory Galactic Evolution Experiment (APOGEE) at the Sloan Digital Sky Survey in the United States, plus additional data from the European Space Agency's Gaia mission.

"Gaia is delivering on its promise: by combining its data with ground-based spectroscopy and galaxy simulations, it allows us to decipher the formation history of our galaxy," said Laurent Eyer of the University of Geneva.

Galaxies grow from the inside out, and the Milky Way is no different, with the average age of stars decreasing with radius from the galactic center. Fiteni's team found that the average age reaches a minimum at a radius of 40,000 light-years from the center. For comparison, our sun is located 26,000 light-years from the galactic center, well inside the star-forming boundary. Beyond this point, the stars begin steadily getting older again, with the oldest stars found both in the center and at the very edge of the Milky Way's disk, creating a U-shaped distribution of ages.

The Milky Way is not unique in having a U-shaped age distribution of stars with radius; other galaxies have also previously been found to share a similar distribution. The computer simulations conducted by Fiteni's team suggest what the cause of this U-shaped age distribution is.

"In astrophysics, we use simulations run on supercomputers to identify the physical mechanisms responsible for the features we observe in galaxies," said João S. Amarante from Shanghai Jiao Tong University in China. "They allowed us to demonstrate how stellar migration shapes the age profile of the disk and to identify where the star-forming region ends."

They found from the simulations that, at a radius of about 40,000 light-years, the efficiency at which the galaxy forms stars suddenly drops, marking the edge of the Milky Way's disk-shaped region of star formation.

So, why are there stars beyond 40,000 light-years if they didn't form there? One big clue is the shape of their orbits.

"A key point about the stars in the outer disk is that they are on close to circular orbits, meaning that they had to have formed in the disk," said Victor Debattista of the University of Lancashire in England. "These are not stars that have been scattered to large radii by an infalling satellite galaxy."

So collisions with other galaxies are not to blame. Instead, what probably happens is a phenomenon called radial migration. Like surfers riding waves to the shore, stars can ride the density waves that form the Milky Way's spiral arms out to greater distances from the galactic center. It takes longer for stars to reach the very edge of the Milky Way's disk, 50,000 light-years or more from the galactic center, explaining why we find the oldest stars on the very fringes of the galaxy.

This all begs the question of why star formation staggers to a halt at 40,000 light-years from the galactic center. One possibility is that it is related to the structure of the Milky Way. Perhaps our galaxy's central bar, measurements of the length of which vary between radii of 11,000 to 15,000 light-years, causes gas to pool out to a certain distance from the galactic center. Alternatively, the warp in our galaxy's spiral disk, which has been attributed to a gravitational interaction with another dwarf galaxy, could disrupt star formation in the galaxy, cutting it off at 40,000 light-years.

The findings were published on April 13 in the journal Astronomy & Astrophysics.

By peering through thick veils of gas and dust, radio astronomers have been able to watch young binary stars orbit around one another in the heart of star-forming clouds — and, in the process, have revealed the stars' masses.

Stars are born in vast clouds of molecular hydrogen gas laced with heavy elements. When one of these clouds fragments into parts, gravity causes pockets within the fragments to collapse, with the density and temperature at the core of each pocket rising. This births a star that continually accretes more gas and becomes more massive.

But what exactly happens to these baby stars next isn't always clear (literally) because they are buried deep within clouds of dark, dusty gas that obscure them. This makes it difficult to observe stars at young ages of perhaps just a few hundred thousand to a million or so years old.

That has been a persistent problem for astronomers seeking to understand how young stars grow and evolve as well as what controls how massive stars become before they switch on, blow away the surrounding gas and stop growing. A star's mass is perhaps the most crucial property that a star has. Its future evolution depends on its mass, which controls its luminosity, temperature and even overall lifetime. Low-mass stars such as red dwarfs vastly outnumber high-mass stars, a distribution astronomers call the 'initial mass function', but why this should be weighted towards lower-mass stars is uncertain — and certainly not helped by the difficulties in observing their growth.

"Stellar mass is the most fundamental property of a star, yet it is notoriously difficult to measure for young, embedded systems," said lead researcher Sergio A. Dzib Quijano, of the Max Planck Institute for Radio Astronomy in Germany, in a statement.

While visible light and, to an extent, infrared light is blocked by these gas clouds, radio waves can pass through unhindered. So, Quijano's team used the Very Long Baseline Array (VLBA) — a network of giant radio telescopes spanning the United States — to resolve young stars in the Orion Molecular Complex. This is a huge region of star formation about 1,300 light years away on average. It includes the famous Orion Nebula as well as the Flame Nebula and the Horsehead Nebula, plus Barnard's Loop, which is a huge arc of molecular gas that spans much of the constellation of Orion as seen in our night sky.

Many stars are formed in binary systems, in which two stars orbit one another around a common center of mass. The VLBA was able to lock onto radio waves from 15 young binary systems within the Orion molecular complex. How the stars in a binary system orbit one another — their orbital period and velocity — depends on the masses of the two stars. Therefore, tracing the orbits of the stars allows astronomers to calculate the masses of the stars, and then compare these to what theoretical work describing the evolution of young protostars says their masses should be.

Quijano's team was able to track the orbits of the 15 binary systems to millisecond accuracy. This enabled the accurate determination of the masses of the stars in seven of the binary systems. For four of these systems, the observations were sensitive enough to allow the astronomers to measure the masses of the component stars from first principles, independent of any guidance from theoretical models. Of these four systems, the team found that all but one had masses that matched what theory said they should be. This tells us that our models are close, but they could still do with some refining.

"These accurate mass measurements now turn Orion into a precision laboratory for testing how young stars form and evolve," said Jazmin Ordonez-Toro of the Universidad Nacional Autónoma de México, who is the second author on the paper describing these findings. "These measurements vastly expand our understanding of how stellar neighborhoods like our own are built."

The findings were published on April 24 in the journal Astronomy & Astrophysics.

Serious stargazing requires planning, right? A dark-sky site, a heavy telescope, a warm jacket. A long drive home. It really doesn't have to be this way. Sure, light pollution maps, Dark Sky Places and Dark Sky Discovery Sites are a stargazer's friend, but don't let a desire for ultimate darkness stop you from connecting with the night sky from anywhere you happen to be.

My favorite places to stargaze aren't necessarily my usual observing spots. If you only wait until you're under a truly dark sky to go stargazing, and you'll likely be hopelessly disoriented and unprepared. However, if you've been topping up your knowledge with micro-sessions — even if it's just the position of the brightest stars and constellations — you'll already recognize its structure. When you finally get a dark sky, you'll be ready to go deeper.

The best preparation is to disorient yourself as much as possible and figure out what you're looking at. Being without the familiar landmarks and usual sightlines of your backyard means working out where everything is. The night sky can be navigated and known, but only by those who don't waste any opportunity to look up.

What's happening and when to look

This week is ideal for a sidewalk stargazing session with the solar system. Any dusk this week — perhaps when you're on the way to or from a yoga class, a restaurant or out walking the dog — look west after sunset for a trio of easy sights.

The simplest is the moon, high in the south. In the west, Jupiter, and below it, slightly to the north, Venus. These three worlds will be hard to miss, even from a city (planets and the moon are practically light pollution-proof). What you're looking at is, of course, the ecliptic — an imaginary line in the sky from east to west that's the same as the path of the sun through the daytime sky. The planets follow the ecliptic, and so does the moon, more or less (when the moon crosses the ecliptic, it can cause an eclipse — hence the name). The ecliptic is the plane of the solar system; all planets orbit the sun along it. I always think of the solar system as a fried egg, with the sun as the yolk and the planets orbiting around it in the white.

Standing on a sidewalk looking at Venus, Jupiter, and the moon gives you something to work with; by joining the dots and heading east, you can draw the ecliptic through the sky.

How and when I do sidewalk stargazing

My own plan this week is deliberately modest. I'll step outside for ten minutes at roughly the same time each evening — around an hour after sunset — and do a quick scan. No equipment, no apps unless I get stuck. I'll start with the moon and note where it sits night by night. Then I'll find Leo in the southeast, using its bright star Regulus as an anchor. From Leo, I'll head to the Big Dipper/The Plow in the north. That's it. If clouds roll in, I'll stop. If I'm tired, I'll stop. The trick is regularity, not endurance.

The biggest misconception is that you need a perfectly dark sky. You don't. You need a consistent routine and a willingness to look up even when conditions are average. In fact, observing from different spots — a sidewalk, a car park, a dimly lit path — forces you to relearn the sky each time. Short, repeated looks at the night sky — even a light-polluted urban sky — reveal that better than any single long session.

Unless you live under Bortle 2 skies, sidewalk stargazing is probably the only way to get to know how the night sky changes from season to season. So next time you're walking home from a pub or restaurant, or taking the dog out before bed, take a minute to stand on the sidewalk and look up — it's a habit that takes you from beginner to recognizing every bright star you can see in an urban sky.

Stargazer's corner: April 24-30, 2026

This week belongs to a bright moon, which reaches full on May 1 — the Flower Moon. Expect increasingly washed-out skies as the days go on, especially after April 27. Over the next few nights, watch the moon drift eastward, passing through the region of the Spring Triangle — Regulus, Spica and Arcturus. By April 29-30, the moon sits close to Spica in Virgo.

Constellation of the week: Leo

Leo is one of the few constellations that actually looks like something without much imagination. After dark, face south and look for a backward question mark of stars — this is the Lion's head, with Regulus at its base. It's also known as the Sickle of Leo. From there, a triangle stretches eastward to form the lion's hindquarters.

Leo is a seasonal marker. When it's high in the south after sunset, it's spring in the Northern Hemisphere. It also sits along the ecliptic, so it often welcomes the moon and planets. Practice finding Leo, and you'll have one of the anchors of the spring night sky as a powerful reference point forevermore.

My latest stargazing obsession: Ursa Major's feet

"Spring up, fall down" is how to remember where the most famous stars in the night sky are right now, as seen from the Northern Hemisphere. I'm talking, of course, about the Big Dipper, called the Plough in the U.K. On April nights, it hangs at the zenith, the point in the sky directly above an observer. The word comes from the Arabic for "path above the head." Its seven stars — Alkaid, Mizar, Alioth, Megrez, Phecda, Merak and Dubhe, all between 58 and 124 light-years away — form a ladle shape, though it's actually part of the constellation Ursa Major, "The Great Bear," which is a much more satisfying shape to find — particularly its three feet all marked by wide double stars (Talitha and Alkaphrah, Alula Borealis and Australis and Tania Borealis and Australis from front to back).

The tail (or handle) of four stars — Megrez, Alioth, Mizar and Alkaid — is home to a circular arc of ultraviolet emission that stretches 30 degrees across the northern sky. Astronomers now think that this Ursa Major Arc may be a shock wave from an explosion or a supernova that happened over 100,000 years ago.

Humanity's exploration of the cosmos is a tale of incredible firsts, discoveries driven by a scientific curiosity that has shaped our understanding of the universe and, ultimately, our place within it.

Join us as we show you where four incredible scientific "firsts" unfolded in the northern hemisphere night sky, ranging from our species' earliest steps on another world, to the first telescopic discovery of a moon by one of history's greatest astronomers and more.

Each target is accompanied by a handy graphic to help point the way. However, if you're unfamiliar with the post-sunset realm, then you may benefit from checking out our guide to the best astronomy smartphone apps, many of which help point the way to specific stars using augmented reality technology.

1 - The first steps on the moon

Apollo 11 set down on the moon and established Tranquility Base on July 20, 1969, marking the first time in history that humans had landed and set foot on the surface of another world. It remains one of the most impressive technological achievements in humanity's short history — one that NASA and its partners are struggling to repeat in the modern day with its Artemis program, decades later.

The Apollo 11 landing site is far too small to spot from Earth. However, you can find the general location of Tranquility Base with the help of a 6-inch telescope or binoculars when the vast basaltic plain of Mare Tranquillitatis (the Sea of Tranquility) is bathed in sunlight in the weeks preceding the full moon.

First, find Mare Tranquillitatis, which appears as a dark scar a little above the lunar equator on the eastern (or right) side of the moon's surface. Next, find the Ritter and Sabine craters to the southwestern edge of the lunar sea. Trace an imaginary line from the bottom of Ritter through the middle of Sabine and follow it for roughly 2.5 times the width of the latter to find the approximate location of the Apollo 11 landing site. You can also find the other five Apollo-era landing sites using our handy observer guide!

2 - The first confirmed exoplanet orbiting a sun-like star

Michel Mayor and Didier Queloz made history in October 1995 when they announced the discovery of the first exoplanet known to orbit a sun-like star. The world, designated 51 Pegasi b, or "Dimidium", is thought to be a "hot Jupiter" — a breed of giant exoplanets that orbit incredibly close to their parent stars.

Dimidium is located 50 light-years from Earth and was only discovered thanks to the minute "wobble" in light from its parent star 51 Pegasi, which arose as the exoplanet's gravity tugged on the host star over the course of its 4-day orbit, according to NASA.

To find the ancient light of the star 51 Pegasi, you'll first need to locate the constellation Pegasus, whose stars glow low on the eastern horizon in the hours preceding sunrise in early spring. Next, find Scheat and Markab — two of the bright stars that form part of the Great Square of Pegasus. 51 Pegasi is a dimmer point of light roughly halfway between the two.

3 - The first star photographed beyond the sun

Astronomer William Cranch Bond teamed up with early photographer J.A. Whipple to capture the first image of a star other than our sun, which they achieved using the Great Refractor telescope at Harvard University on the night of July 16-17, 1850.

About 145 years later, the red giant Betelgeuse would become the first star beyond our sun to have its surface directly imaged by astronomers using the Hubble Space Telescope, as it glowed around 650 light-years from Earth in the constellation Orion.

Vega is found rising above the northeastern horizon in the constellation Lyra after sunset in early spring and soars high overhead as the night wears on, before finally fading from sight almost directly overhead as the sun rises.

4 - The first moons discovered with a telescope

The invention of the telescope in the early 1600s saw the discovery of hitherto unknown moons and planets orbiting within our solar system. The first such discovery was made by famed astronomer Galileo Galilei in 1609, who observed Jupiter with his own version of a "spyglass" telescope and was surprised to find four star-like objects orbiting the gas giant.

We now know those objects to be the natural satellites Io, Europa, Ganymede and Callisto, which astronomers refer to as the Galilean moons in honor of their discoverer. The moons are easy to spot with any modern-day telescope with an aperture of 4-inches or more, or a pair of binoculars!

To follow in the footsteps of Galileo, you simply need to find Jupiter glowing as a steady point of light close to the dimmer stars of the constellation Gemini above the western horizon at sunset. The Galilean moons will appear as bright specks of light arrayed in a line around the gast giant's disk through a small telescope, much like they did to the old master when he discovered them hundreds of years ago.

Feeling inspired to explore the wonders of the night sky up close? Then be sure to check out our roundups of the best telescopes and binoculars, along with our expert's tips for new stargazers.

Editor's Note: If you would like to share your astrophotography with Space.com's readers, then please send your photo(s), comments, and your name and location to spacephotos@space.com.

A galaxy dying is not a gentle thing. Its star-making factories, once churning out millions of suns, grind to a halt. Rather than a slow fade, it's a sudden, striking shutdown, a phenomenon astronomers call rapid quenching.

Such phenomena are the mysteries of what we call post-starburst galaxies, which present some of the most compelling, yet often overlooked, stories unfolding across the universe. For astronomers, such systems are like cosmic crime scenes. They recently had a massive burst of star formation — a party of epic proportions — but now show almost no new stars being born. It's like finding a ballroom where the music just stopped, the lights went out, and everyone left in a hurry. The scene leaves us wondering about the sudden emptiness. And about the astonishing speed of their exit.

Here's the rub: post-starburst galaxies are pretty rare. They make up less than 1% of all galaxies out there. This rarity makes them tricky to study. Early on, astronomers looked at optical light, specifically strong absorption lines from hot, young A-type stars, combined with a distinct lack of emission lines that signal active star formation. But these methods, developed years ago, sometimes missed a whole bunch of post-starbursts, meaning our picture was incomplete.

To truly understand what happens when a galaxy suddenly stops forming stars, we need to know what fuels star formation in the first place: gas. Cold gas, to be precise. You see, stars don't just appear out of nowhere; they're born from dense, chilly clouds of molecular hydrogen. If a galaxy runs out of this molecular gas, or if the gas gets disrupted and can't coalesce, star formation shuts down. Simple, right?

Not so fast. Previous studies on these fascinating, transitioning galaxies were a bit of a hodgepodge. They used inconsistent selection criteria, had varying sensitivities in their observations, and often worked with samples that were just too small to give us a clear, unified picture. It meant we had conflicting clues, and no coherent narrative for our cosmic whodunit. Some even suggested galaxies could still be chock-full of gas but somehow not forming stars, which would be a real head-scratcher for anyone trying to understand stellar nurseries.

Other researchers, though, showed that many of those seemingly gas-rich, quiet galaxies actually had star formation going on, just hidden behind thick clouds of dust, appearing "obscured" in optical observations. So, the picture was fuzzy, to say the least, and left a big hole in our understanding.

Enter the EMBERS I study, a truly clever piece of astronomical detective work. Led by Ben F. Rasmussen from the University of Victoria and his colleagues from institutions like the Space Telescope Science Institute and the University of St. Andrews, this team decided it was time for a comprehensive, multi-pronged attack on the problem. They set out to perform the first uniform assessment of both atomic and molecular gas in a large, well-selected sample of post-starburst galaxies. It's like bringing in the full CSI team after years of relying on a single, blurry photograph.

They started with a list of 114 candidate galaxies pulled from the Sloan Digital Sky Survey, carefully picked out based on their stellar mass and distance. Then came the heavy lifting: staring at these galaxies for a really, really long time. To sniff out the atomic hydrogen — the more diffuse, cooler gas that acts as the initial, sprawling reservoir for future star formation — the team harnessed the immense power of China's Five Hundred-metre Aperture Spherical Telescope (FAST). That's a whopping 500-meter--wide (1,640-foot) dish, ideal for picking up faint signals from far away.

But the real star-making fuel is molecular hydrogen, and that's much harder to spot directly. So, astronomers use a trusty tracer: carbon monoxide, or CO. Think of it like a smoke detector for molecular clouds; where there's CO, there's likely H2 ready to collapse and form stars. To measure this CO emission, Rasmussen and his colleagues spent an astounding 188.9 hours, split across four different observation proposals, using the IRAM 30-meter telescope. That's a lot of late nights and early mornings staring at the sky. They obtained 52 new observations, combining them with nine archival ones for their total sample of 61 galaxies.

The big reveal is that, on average, post-starburst galaxies are indeed depleted in molecular hydrogen compared to their actively star-forming progenitors. We're talking about a significant drop — somewhere between 0.3 to 0.6 times less molecular gas than what you'd find in galaxies of similar stellar mass that are still cranking out stars. This strongly suggests that a key mechanism for rapid quenching is a galaxy simply running out of its star-forming fuel.

In other words, the party ends because the cosmic snack bar is empty.

But here's where the story gets really interesting, and less straightforward. This isn't to say every single post-starburst galaxy is totally barren. The study found a striking diversity in their cold gas reservoirs. Some of these galaxies, even after their dramatic starburst shutdown, still had molecular gas fractions ranging from a modest 2% of their stellar mass all the way up to a whopping 250% in the detected cases.

So, while the average post-starburst galaxy is indeed gas-starved, the individual stories are far more complex. This diversity has huge implications for understanding galactic evolution. It means there isn't just one universal rapid shutdown mechanism. For some galaxies, the shutdown might be irreversible, a truly permanent end to star formation, likely due to severe gas loss. For others, particularly those that retain a good chunk of gas, there's a tantalizing possibility of rejuvenation — a second act, where star formation could kick off again, albeit temporarily, leading to a temporary cessation rather than a terminal one.

A striking new image from NASA's newest space telescope reveals vast reservoirs of water ice stretching across one of the Milky Way's most chaotic stellar nurseries, offering a glimpse into where much of the universe's water — including that found in Earth's oceans — may originate and be stored.

The observations, captured by SPHEREx, map icy material across the turbulent Cygnus X region, a massive star-forming complex filled with dense clouds of gas and dust where new stars are rapidly emerging. The snapshot, based on data collected in 2025 and released this week, highlights water ice in bright blue alongside intertwining dark dust lanes that weave through the region, dotted with pinpricks of light from newborn stars.

The findings show that these ice reservoirs are composed of molecules such as water, carbon dioxide and carbon monoxide, marking key ingredients in the chemistry that can ultimately lead to life as we know it. Scientists think these ices, frozen onto the surfaces of tiny dust grains, represent a major source of the universe's water. Furthermore, the same processes that form and preserve the reservoirs are thought to seed planetary systems. This means the water in Earth's oceans and ices found on comets and other planetary bodies likely originated in such regions.

"These vast frozen complexes are like 'interstellar glaciers' that could deliver a massive water supply to new solar systems that will be born in the region," Phil Korngut, a SPHEREx instrument scientist and researcher at the California Institute of Technology, said in a statement.

"It's a profound idea that we are looking at a map of material that could rain on nascent planets and potentially support future life."

Researchers say they expected SPHEREx to find these ices only in front of individual bright stars, where starlight acts like a spotlight revealing any intervening material.

"But this is something different," study lead author Joseph Hora, an astronomer at the Center for Astrophysics (CfA) at Harvard & Smithsonian in Massachusetts, said in the same statement.

To the surprise of the mission team, SPHEREx captured diffuse background light passing through "entire dust clouds" along the galactic plane, where most of the galaxy's stars, gas and dust are concentrated.

"SPHEREx can see the spatial distribution of the ices they contain in incredible detail," said Hora.

The study supports a long-standing idea that interstellar ice forms on the surfaces of tiny dust grains "no larger than particles found in the smoke from a candle," the NASA statement says.

The findings also show that water ice is not evenly distributed but instead concentrates in the densest regions of cosmic dust, which act as protective shields and block harsh ultraviolet radiation from nearby newborn stars and allow those fragile molecules to survive across eons.

As SPHEREx continues its planned two-year all-sky survey, researchers say they are excited to build an increasingly detailed map of how water and other molecules, like carbon dioxide, are distributed across the Milky Way, and how they respond to varying levels of ultraviolet radiation.

"This is just the beginning for the mission," the NASA statement read.

A study about these results was published on April 15 in The Astrophysical Journal.

The spectacular birthplace of weird carbon molecules known as "buckyballs" came to light in new imagery of a nebula from the James Webb Space Telescope. The gas cloud includes an upside-down question mark shape, which marks a structure scientists don't yet understand.

The James Webb Space Telescope (JWST) peered 10,000 light-years into space to trace the origin of buckyballs, which are large and hollow molecules resembling a soccer ball. The gas cloud the observatory imaged, known as Tc1, came from a dying star, in the constellation Ara (Latin for "alter") in the southern hemisphere.

"Tc 1 was already extraordinary, as it was the object that told us buckyballs exist in space, but this new image shows us we had only scratched the surface," Jan Cami, a physics and astronomy professor at Western University in Canada, said in a statement. "The structures we're seeing now are breathtaking, and they raise as many questions as they answer."

Cami also led the team that first found cosmic buckyballs in 2010, a discovery notable enough to be published in the journal Science. That study was conducted using NASA's Spitzer Space Telescope which, like JWST, observed in infrared wavelengths.

But Spitzer's mission ended in 2020. JWST, which has a larger mirror and is further away from Earth, can now pick up where Spitzer left off and zoom in on the details.

Ingredients of life

Buckyballs are more properly known by their chemical name, buckminsterfullerene. This form of carbon is named after Buckminster Fuller, a space futurist and architect known for his work on hemispherical structures called geodesic domes. Buckyballs somewhat resemble the domes, which is how they got their name in a 1985 paper led by Harry Kroto at the University of Sussex. Some team members, including Kroto, later earned the 1996 Nobel Prize in Chemistry based on the paper. Decades later, however, the origin story of these carbon spheres remains enigmatic.

Buckyballs are significant as a type of polycyclic aromatic hydrocarbons (PAHs), which are a class of organic compounds — essentially, ingredients of life. Each of these PAHs has unique "signatures" or spectra of light, although they share properties because they are part of the same family, Cami said.

"We are now in a situation where we can actually see, especially within this object, how these buckyballs change as a function of changes in temperature, density and radiation field," Cami told Space.com. The insights from this discovery could provide insights into how organic molecules form and evolve.

"We find them [buckyballs] in many more objects, of very different kinds," Cami said. "It's not just dying stars. We also find them in young stars. We see them in interstellar clouds. In star-forming regions. We've also found them in meteorites. So we see them essentially everywhere … but we don't see them very frequently. And that's a bit of the mystery."

How the sun will die

The gas cloud JWST observed, known as Tc 1, includes a star similar in size to our own sun — but much older. The star has no more fuel to burn and has shed layers of gas and dust in a series of shells, blasting out into space. What's left behind is a glowing core, known as a white dwarf, which is sending out radiation that causes the gas shells to glow.

It was near this star where Cami's team first spotted buckyballs in 2010, and there were many reasons for a revisit. JWST not only has higher resolution allowing for much finer details in observations, but in the intervening years, few other such "planetary nebula" like Tc 1 (the moniker has to do with the shape of the gas, not with planets) have been found with buckyballs.

"In several hundred planetary nebulas, we found them in like a handful. Maybe 10 at most. And why in those 10 and not in the other ones, we still don't know," Cami said.

Scientists are planning a detailed look at Tc 1, as the analysis is just beginning, to figure out if buckyballs formed in this region similarly to how they do on Earth. (Cami said how terrestrial buckyballs form is a little obscure, although it tends to involve large amounts of carbon, low oxygen, and high temperatures.)

The team also wants to know why cosmic buckyballs are emitting infrared wavelengths in a way not predicted by models of how ultraviolet radiation is absorbed.

"None of our models actually correctly predicts what the correct emission would be, and that tells us that there's something about these processes that we haven't fully figured out. Maybe we're missing some processes. Maybe our laboratory experiments for some of the parameters that we need, are not as accurate as we need them to be," Cami said.

Box in a box

A first step is mapping where the buckyballs are located. Morgan Giese, a physics and astronomy PhD candidate at Western, discovered the buckyballs are mostly surrounding the white dwarf in their own shell. In a statement, Giese called the shape "buckyballs arranged like one giant buckyball", and added why that is happening is a mystery.

Other details are coming soon from the JWST image, which was taken with the telescope's mid-infrared instrument or MIRI. Saunders Secondary School science teacher K. Beecroft processed the image, Cami said; they met through school-outreach events at Western, and also connected through the university's observatory program.

"She's an amateur astronomer … I've been very impressed with her images, and so I asked her if she was interested in doing this. Within just a few hours, she sent me this image. I was like, 'Holy cow.'"

Aside from tracing the filaments of gas, the telescope spotted spectroscopic details that will be released soon in a series of science papers. One of the papers will talk about that infrared-emission mystery, Cami said, with the details forthcoming once an embargo lifts.

"We're actually looking at what the physical processes are that essentially cause the buckyballs to emit in infrared. We found that there's a few more processes at play than we actually thought before," he said.

More generally, the observations not only are showing the birthplace of buckyballs, but what happens to the environment as a dying star collapses: that would be the nebula's temperature, chemical components, density and gas motions. Scientists are calling this the first-ever detailed view of a planetary nebula, and are hoping to bring their insights to similar nebulas elsewhere.

Cami's team was awarded more time on JWST to look at two other planetary nebulas in the fall, which also have a lot of buckyballs visible in their spectrum. "What's different in those objects is essentially that the radiation field is very different. So we picked those to see, to really study, what is the impact of the radiation field," Cami said.

The team suggests that photochemistry and photophysics — chemistry and physics driven by light emissions — likely influences how those environments are shaped, but understanding just how will require more study.

A pristine star found to be devoid of almost any elements heavier than hydrogen and helium might be the immediate descendent of one of the first stars in the universe.

If stars were like myths, then the first generation of stars to have existed in the cosmos would be like the gods of ancient Greece — massive, mysterious and profoundly influential on what came after them.

We call these first stars "Population III" stars, Population I stars being younger stars like the sun, and Population II being the stars that formed during the several billion years after the first stars.

Yet no one has ever seen one of these first stars either, "because they were massive, lived fast and died young, or the lowest-mass Population III stars that could persist to the present day are extremely rare," said Kevin Schlaufman of Johns Hopkins University in a statement.

So while we still haven't seen a Population III star, a star called SDSS J0715-7334 is the next best thing – a star that formed from an almost pristine cloud of gas that had been tainted by heavy elements formed in the supernova blast of a Population III star.

SDSS J0715-7334 was initially identified by Schlaufman in data from the Sloan Digital Sky Survey in 2014, and then independently discovered in 2025 by a team of students led by Alexander Ji of the University of Chicago.

In the first three minutes after the Big Bang, only three elements existed: hydrogen, helium and the tiniest traces of lithium. This is all that the universe had to work with to form the first stars. All the other elements in the periodic table had to be subsequently formed by stars, beginning with the supernova explosions of the most massive Population III stars.

The heavy elements produced in the violent death of one first generation star swiftly polluted a primordial cloud of molecular hydrogen and helium that subsequently collapsed to form SDSS J0715-7334. This would have happened during the first couple of hundred-million years after the Big Bang.

Using the high-resolution Magellan Inamori Kyocera Echelle spectrograph on the 6.5-meter Magellan Clay Telescope at Las Campanas Observatory in Chile, a team led by Ji and including Schlaufman followed up on SDSS J0715-7334 to quantify its abundance of heavy elements, which astronomers refer to as "metals" but which include elements such as carbon and oxygen as well as the likes of aluminum and iron.

Our sun is made of 74.9% hydrogen, 23.8% helium and 1.3% metals, indicative of the many generations of stars across cosmic time that have built up the abundance of heavy elements in the universe. On the other hand, Ji and Schlaufman's team found that SDSS J0715-7334 is almost exclusively hydrogen and helium with only 0.005% the abundance of metals that our Sun possesses. No other star has been found to be so pristine with so few heavy elements. The previous record holder, a star in our Milky Way cataloged as SDSS J1029+1729, has twice the abundance of heavy elements that SDSS J0715-7334 has.

"The star [SDSS J0715-7334] has so little carbon that it suggests an early sprinkling of cosmic dust is responsible for making it," said Ji in another statement.

"While this star does not have a primordial composition itself, it is the closest that astronomers have ever gotten to the Population III stellar generation on this particular metric," added Schlaufman.

From its chemical composition, Ji and Schlaufman's team were able to work backwards to deduce the mass of the star and the energy of its supernova that produced the debris to pollute SDSS J0715-7334’s birth cloud. They found that the Population III star that died had a mass of at least 30 times that of our sun, and that its supernova explosion was more energetic than is typical today.

SDSS J0715-7334 was discovered 80,000 light-years away, where it appears to be migrating from the outer halo of the Large Magellanic Cloud (LMC), hence why Ji's students nicknamed the star the "Ancient Immigrant."

Along with its companion the Small Magellanic Cloud, the LMC is a recent arrival to the Milky Way's shores, and for much of their history the Magellanic Clouds were not forming stars and building up their chemical inventory. It's only since they've been close to the gravitational influence of the Milky Way that things have really kickstarted within them.

"It's possible that we're going to find a relatively higher proportion of ultra-metal-poor stars in galaxies like the Magellanic Clouds than in our own Milky Way galaxy," said Schlaufman.

The Sloan Digital Sky Survey is an excellent tool for hunting down ancient, pristine stars such as SDSS J0715-7334. Located at Apache Point Observatory in New Mexico, it performs sweeping surveys of the night sky, making optical and infrared spectroscopic measurements of millions of stars and galaxies.

"There is still lots to be done to understand what actually was going on in that era long, long ago when the Milky Way was young," said Schlaufman. "We've only scratched the surface with this current phase of the Sloan Digital Sky Survey."

The research was published in the April 3 edition of Nature Astronomy.

Artificial lights at night brightened up planet Earth by 16% between 2014 and 2022, a new study using satellite images has revealed.

But some areas, including those struck by war and natural disasters, or those in countries with effective light pollution and energy-saving policies in place, are bucking the trend.

From space, Earth at night is a magnificent sight — a darkened sphere lined and dotted by blueish and golden lights revealing outlines of countries and continents. It has not always looked like that. For our ancestors, that twinkling ball would have been completely dark. Artificial lights at night reveal the progress of civilization as new settlements spring up and electric grids expand, bringing the comforts of modern life. But constant artificial light has also become a problem, affecting sleep quality, disrupting plant and animal biorhythms and obstructing our views of the cosmos.

The new study, by an international team of researchers. found that Earth is getting brighter overall. But there are caveats: In many areas, lights have actually been extinguished by war and natural disasters, or dimmed by effective energy-saving policies. In fact, Zhe Zhu, the study's lead author, said that, despite the overall brightening visible in the satellite images, the world's dimming areas are actually increasing in size at an accelerating pace.

"We found that the Earth is not gradually brightening, it is flickering," said Zhu, an associate professor of remote sensing at the University of Connecticut. "The brightening is mostly driven by developing countries like India, China and parts of Africa. But we also see the areas of dimming increasing every year. Some of that is due to sudden events like wars and natural disasters, but we also see a huge area of dimming in Europe, where they put policies in place. The U.S. is still mostly increasing."

A dramatic decline in night-time artificial light was observed, for example, in Ukraine following the Russian invasion, which began in February 2022. France, a developed western European country, dimmed by a staggering 33% thanks to new policies.

Zhe said the study is the first to reveal the trends in artificial light use with a level of temporal detail that distinguishes individual events and regional trends. The researchers could thus see in the data the rollouts of the COVID pandemic lockdowns across the world and monitor phases of armed conflicts.

"You can see almost in real time when there is a war happening," said Zhe. "In Palestine, you could see many dips — ups and downs — every time the war flares up. You can also see disasters, such as major hurricane impacts in Puerto Rico, which basically wipe out electricity for a long time."

The researchers used data from NASA's Black Marble tool, which uses special algorithms to process measurements from the Visible Infrared Imaging Radiometer Suite (VIIRS). The VIIRS instrument flies on both the Suomi National Polar-orbiting Partnership (NPP) satellite, a joint effort of NASA and the U.S. National Oceanic and Atmospheric Administration, and its predecessor, NOAA-20. VIIRS captures a wide range of light signatures, from ultraviolet to infrared light, revealing the nighttime glow of the planet.

The algorithms, Zhu explained, filter out unwanted noise such as moonlight reflections, auroral light, the shadowing by clouds and vegetation, and even differences caused by the viewing angle of the satellite during different passes.

The brightness increases reported in this study, however, may be somewhat skewed, as the satellite sensors feeding the NASA Black Marble tool are not sensitive to the blue-tinged light emitted by most traditional LED lights, which dominate the lighting technology of today, Zhe said.

A 2023 study, based on more than 50,000 observer reports from all over the world, concluded that the perceived night sky brightness in inhabited locations worldwide had been increasing at a mind-boggling rate of nearly 10% per year in the past decade. This brightness increase is effectively erasing stars from the night sky, forcing skywatchers and professional astronomers to retreat into ever more remote locations. The incessant glow, which prevents true darkness from setting in even in the dead of night, also has profound effects on human, plant and animal health, disrupting sleep and natural growth cycles.

"Human vision at night is most sensitive towards shorter wavelength (blue) light and has little sensitivity to near infrared light, but the VIIRS has no sensitivity to light below 500 nm (i.e. blue light), and can easily see infrared light from high-pressure sodium lamps," Christopher Kyba, a professor of night-time light remote sensing at Ruhr University Bochum in Germany and one of the co-authors of the paper, told Space.com in an email. "So, when a city converts a street from high-pressure sodium to white LED, then a person would say it got brighter, but the satellite would say it got darker."

Kyba also led the 2023 observer study.

Zhe says the brightening isn't just a doom-and-gloom signal for skywatchers. In many areas, especially underdeveloped regions of Africa and Asia, the lights mean improved economic prosperity.

"From the economic perspective, brightening can be a good thing," he said. "It means more activity, people having access to power where they previously didn't have it."

The study was published in the journal Nature on Wednesday (April 8).

Astronomers have discovered dozens of faint ribbons of stars in the outskirts of the Milky Way using data from the European Space Agency's Gaia mission.

The findings were made using a new algorithm that more than quadruples the number of known candidates of these so-called "stellar streams." This discovery could offer fresh clues about how our galaxy evolved and how its dark matter is distributed, the study's researchers say.

Stellar streams are arcing threads of stars that form when compact star clusters travel through the Milky Way's gravitational field, shedding stars that are stretched out into long, trailing ribbons.

"It's like riding a bike with a bag of sand, only the bag has a hole in it," study co-author Oleg Gnedin, a theoretical astrophysicist at the University of Michigan, said in a statement. "Those grains of sand are like the stars left behind along their trajectory."

Finding stellar streams is valuable because the shapes and motions of these phenomena preserve a record of what gravitational forces have acted on them over time. That makes them powerful tools for mapping the Milky Way's mass, and that mass measurement would include its elusive dark matter halo — dark matter being the invisible "glue" thought to hold galaxies together, but has yet to be observed directly despite decades of effort.

The new study, led by Yingtian "Bill" Chen of the University of Michigan, identifies 87 stellar stream candidates associated with globular clusters, which are dense, ancient groupings of stars that orbit the Milky Way. Previously, fewer than 20 stellar streams had been identified, often only serendipitously in Gaia data, leaving astronomers with too small a sample size to draw broad conclusions.

Most known stellar streams come from dwarf galaxies or clusters that have already been largely torn apart. Streams from still-surviving globular clusters, like those identified in the new study, are much rarer and especially useful because astronomers can compare the stream directly with its parent cluster.

To find them, Chen developed a computer algorithm called StarStream, which searches for streams using a physics-based model rather than relying on visual patterns alone, according to the study. The team then applied the method to Gaia data, which from 2014 to 2025 mapped the positions and motions of billions of stars in the Milky Way.

"It turns out that it's a lot easier to find things when you have a theoretical expectation of what you're looking for when you have a simple phenomenological picture," Gnedin said in the statement.

The results also revealed that many streams do not match the classic expectation of thin, well-aligned trails. Instead, the study reports that some of the newfound streams are shorter, wider or even misaligned with their parent clusters' orbits — suggesting earlier searches may have missed them by focusing only on the most obvious structures.

The expanded sample also provides evidence that some diffuse globular clusters are shedding stars at unusually high rates, a sign they may be nearing complete tidal disruption, the study reports.

Not all 87 candidates are expected to be confirmed, however, as some detections have lower confidence due to background contamination from unrelated stars, the researchers say.

The study's results, along with the algorithm applied to them, can be tested with upcoming observations from next-generation facilities — including the Vera C. Rubin Observatory, NASA's Nancy Grace Roman Space Telescope and the Dark Energy Spectroscopic Instrument — to help verify which streams are real, Chen said in the statement.

"It'll be very easy to adjust the algorithm to future missions," he said. "Once we have the data, it will be very straightforward to apply it."

This research is described in a paper published March 23 in The Astrophysical Journal.

Astronomers have discovered that rapidly spinning dead stars called neutron stars at the heart of pulsars can blast out radio signals from their edges. The finding could overturn decades of thinking suggesting that pulsars only blast beams of radiation from close to their surfaces and at their poles.

Pulsars, like all neutron stars, are created when massive stars run out of fuel needed for their internal nuclear fusion process and thereby collapse, forming a stellar remnant with matter so dense that if a teaspoon of it were brought to Earth, it would weigh around 10 million tons. This collapse also generates the universe's most powerful magnetic fields — and, like the cosmic equivalent of an ice skater drawing in their arms to increase their speed, the collapse can also speed up the spin of neutron stars to as much as 700 times a second.

When these rapidly spinning neutron stars blast out radiation from their poles, that radiation sweeps across the cosmos like beams of light from a cosmic lighthouse. And it is these cosmic lighthouses are known as pulsars. In fact, the rotation rate of pulsars are so accurate and well-regulated that they can be used as highly precise universal "clocks."

The team behind the new research examined radio observations of around 200 rapidly spinning pulsars, or millisecond pulsars, comparing them to data collected in gamma-rays. This revealed radio waves emanating from two or more regions surrounding around 33% of these millisecond pulsars. Only 3% of slower-rotating neutron stars have been observed to emit radio waves from a region within their grasp besides their poles.

Then the fact that the more distant radio wave pulses aligned with gamma-ray blasts from these pulsars detected by NASA's Fermi Space Telescope indicated to the team that both types of electromagnetic radiation were being emitted from the same non-polar and distant regions around these pulsars.

"As we are detecting signals both from the stars' surfaces and from the very edge of their magnetic reach, this study shows that these tiny, fast-spinning stars are even more complex and surprising than we thought," team member Simon Johnston from Australian science agency CSIRO (Commonwealth Scientific and Industrial Research Organisation) said in a statement.

The team concluded that these factors indicate millisecond pulsars produce radio waves close to the poles of these dead stars and in a swirling "current sheet" of charged particles — that are more distant from the neutron star and beyond its magnetic fields — which sweep around with the motion of the dead star.

Current sheets were already known to be responsible for the gamma-ray emission of millisecond pulsars, so the alignment between radio waves and gamma-rays indicates a shared origin point.

This could also explain why some millisecond pulsars have strange, broken-up radio wave profiles. What astronomers observe, be it radio waves from the poles, from the current sheet, or both, depends on how the pulsar is oriented in relation to our telescopes.

One useful outcome of this research and its findings is the fact that millisecond pulsars should be easier to detect than astronomers had previously theorized. That's because the radio waves are emanating over a wider range of directions rather than just in a narrow cone from the poles. That means a pulsar doesn't have to be perfectly aligned with Earth to be observed via its radio emissions.

While this is good news for projects such as the measurement of ripples in spacetime called gravitational waves that use large arrays of pulsars, the team is still puzzled about how radio pulses can be generated so far away from neutron stars and the turbulent immediate environments they generate.

"Understanding where their signals come from — and why they look the way they do — is essential for using them as precision instruments," team member Michael Kramer from the Max Planck Institute for Radio Astronomy (MPIfR), Germany, said in the statement.

The team's results were published on March 25 in the journal Monthly Notices of the Royal Astronomical Society.

Astronomers have used the XRISM (X-Ray Imaging and Spectroscopy Mission) X-ray spacecraft to discover that a star is being slowly devoured by an elusive stellar companion, solving a mystery that has baffled scientists for over a century.

The star in question is named gamma-Cas, located around 550 light-years away and visible with the unaided eye over Europe on clear nights as the peak of a distinctive "W" in the constellation Cassiopeia. The star gamma-Cas, which is 19 times the size of the sun and up to 65,000 times brighter than our star, first became a puzzle in 1866 when it was found to possess a bright hydrogen "fingerprint" unlike other stars such as the sun.

In the 1970s, this puzzle turned into a full-fledged mystery as astronomers also discovered gamma-Cas shines brightly in high-energy X-rays. These were estimated to originate from plasma burning at an incredible 150 million degrees, shining 40 times brighter than a typical massive star.

Decades later, scientists would theorize that these strange emissions came from a rotating disk of stellar material that had been ejected by the rapidly spinning star. Over time, such disks can build up and then disperse, causing the brightness of the star to fluctuate. Now, thanks to the sensitivity of XRISM (pronounced "crism"), astronomers have discovered the presence of a compact companion, likely a white dwarf star, that is pulling material away from gamma-Cas. White dwarfs are often called "dead stars" because they represent the core remnant of a star that exhausted its fuel supply needed for its intrinsic nuclear fusion processes.

"There has been an intense effort to solve the mystery of gamma-Cas across many research groups for many decades. And now, thanks to the high-precision observations of XRISM, we have finally done it," team leader Yaël Nazé of the University of Liège, Belgium, said in a statement.

Two competing theories

The hydrogen feature of gamma-Cas resulted in the development of a new classification of stellar bodies, so-called Be stars ("B" representing massive, hot blue stars and "e" representing the unique hydrogen signal). Thanks to the proliferation of X-ray space telescopes like XRISM, XMM-Newton, Chandra and eROSITA, astronomers have now discovered over 20 stars with gamma-Cas-like X-ray emissions, resulting in a special family within the wider category of Be stars.

Scientists posited two explanations for the unusual X-ray emissions of stars like gamma-Cas. Either they are the result of the stars' magnetic fields interacting with surrounding plasma disks, or they are the result of stripped material falling onto the surface of an unseen companion white dwarf star. This research confirms the validity of that latter theory.

"The previous work using XMM-Newton really cleared the way for XRISM, enabling us to eliminate numerous theories and prove which of the last two competing theories was correct," Yaël said. "It's extremely satisfying to have direct evidence to solve this mystery at long last."

There are still some puzzles surrounding gamma-Cas and other high-energy X-ray emitting stars. Such pairings between stars and white dwarfs were once expected to be common, especially for low-mass stars. Recently, however, scientists have found that such pairings are rarer than previously estimated and occur for high-mass Be stars.

"We think the key is in understanding how exactly the interactions take place between the two stars," Yaël added. "Now that we know the true nature of gamma-Cas, we can create models specifically for this class of stellar systems, and update our understanding of binary evolution accordingly."

The team's research was published on Tuesday (March 24) in the journal Astronomy & Astrophysics.

Brown dwarfs may have gained the unfortunate nickname "failed stars," but new research suggests they can collide and merge for a second chance at success.

Brown dwarfs are cosmic objects with around 13 to 80 times the mass of Jupiter, making them around 0.013 to 0.08 times as massive as the sun. They are deemed as having "failed" because despite forming like normal stars — when vast, overly dense patches of matter collapse in interstellar clouds of gas and dust — they fail to gather enough mass from these clouds to trigger the nuclear fusion of hydrogen to helium in their cores, the process that defines a "main sequence" star, like the sun.

However, after searching through observations collected by the Zwicky Transient Facility (ZTF) at Palomar Observatory, a team of scientists has discovered a tightly orbiting pair of brown dwarfs that are working together to combat this "failure." One brown dwarf is actively siphoning material from its companion, meaning it could achieve the mass needed to trigger nuclear fusion in its core and become a fully-fledged star. Either that, or these brown dwarfs will collide and merge, birthing an entirely new star with enough mass to trigger nuclear fusion.

"The failed stars get a second chance," team leader Samuel Whitebook, from California Institute of Technology (Caltech), said in a statement. "Brown dwarfs don't have internal engines like stars do, but this result shows they can exhibit very interesting dynamic physics."

The team's findings are extraordinary because, though similar mass transfer has been seen in binary objects before, this has occurred between stellar bodies with far greater masses.

"These are very exotic objects," team member Tom Prince of Caltech said. "We've told some of our colleagues about them, and they didn't believe such a thing exists."

The brown dwarf pairing at the heart of this discovery, found in the ZTF Variability Archive, is designated ZTF J1239+8347 (ZTF J1239) and is located around 1,000 light-years away in the constellation Ursa Major. The two brown dwarfs, both 60 to 80 times as massive as Jupiter, orbit each other so tightly that the entire ZTF J1239 system would fit between Earth and the moon.

The researchers can't be sure how these brown dwarfs initially came to orbit each other, but they suspect that the failed stars were pulled from separate systems and pushed together by the gravitational influence of another star. Once orbiting each other, the brown dwarfs would have gradually spiraled closer and closer together, with the gravitational influence of one brown dwarf causing its counterpart to puff out and become less dense.

"When one star's gravity is overcome by the other's, matter starts flowing from the less dense star to the denser star," Whitebook said. "It's like the matter sloughs off through a nozzle."

This "nozzle" sprays matter from the puffy brown dwarf to one spot on its denser companion. This region is heated and begins to glow brightly. As this bright spot rotates with its parent brown dwarf, it generates a significant change in the brightness of this system every 57 seconds. It is this signal that first made this system stand out among the 2 billion objects of the ZTF Variability Archive.

This is the first mass transfer process seen in a brown dwarf pairing, but the team believes there could be many more brown dwarf pairings such as this just waiting to be uncovered.

"We expect the Vera Rubin Observatory [a major ground-based observatory in Chile] to detect dozens more of these objects," Whitebook concluded. "We want to find more to understand the population and how common it is. We predict this happens more than you think."

The team's research was published on Wednesday (March 18) in The Astrophysical Journal Letters.

Scientists have adopted the role of "cosmic archaeologists" to discover a rare, iron-deficient second-generation star — essentially a fossil record of our universe's chemical evolution. Just as uncovering artifacts here on Earth teaches us about lost generations of humans, this observation provides hard evidence of how the first generation of stars died to chemically enrich their successors.

The second generation, or POP II, star was discovered in the dwarf galaxy Pictor II, located around 150,000 light-years from Earth in the constellation Pictor, using the Dark Energy Camera (DECam) mounted atop Víctor M. Blanco 4-meter Telescope. Designated PicII-503, the star has only 1/40,000th of the iron contained within the sun, which is a third-generation, or (somewhat confusingly) POP I, star. The fact that PicII-503 has the lowest concentration of iron ever seen beyond the Milky Way makes it one of the most primordial stars ever discovered.

That deficit isn't the most extraordinary about PicII-503, however. The team also found that this POP II star has a massive overabundance of carbon, with its ratio of carbon-to-iron over 1,500 times greater than the same ratio in the sun. This overabundance mirrors the unique carbon signature of low-iron stars found in the nebulous outer halo of the Milky Way.

"Discoveries like this are cosmic archaeology, uncovering rare stellar fossils that preserve the fingerprints of the universe’s first stars," Chris Davis, National Science Foundation Program Director for NOIRLab said in a statement.

A kind of magic

The first stars in the universe, or POP III stars, were born when the chemical abundance of the cosmos didn't extend beyond hydrogen, helium, and a smattering of heavier elements, which astronomers collectively call "metals. "This meant that these POP III stars were also dominated by hydrogen with just a little helium and very little in terms of metals. These stars forged the first carbon and iron in their cores, material that was distributed into the interstellar medium when these stars went supernova and exploded at the end of their lives.

Interstellar clouds of gas and dust enriched with these metals eventually cooled and collapsed to birth the second generation of stars, stars that were more metal-rich thanks to the donation of heavy elements from their predecessors. That makes POP II akin to time capsules, recording an important stage in the chemical enrichment of the universe.

"Discovering a star that unambiguously preserves the heavy metals from the first stars was at the edge of what we thought possible, given the extreme rarity of these objects," team leader Anirudh Chiti of Stanford University said in the statement. "With the lowest iron abundance ever derived in any ultra-faint dwarf galaxy, PicII-503 provides a window into initial element production within a primordial system that is unprecedented."

The first confirmed example of a POP II star found in a faint dwarf galaxy, PicII-503 was highlighted as an extremely metal-poor star in data collected by DECam's MAGIC (Mapping the Ancient Galaxy in CaHK) survey. This 54-night observing endeavor was developed with the explicit purpose of identifying the oldest and most chemically primitive stars in the Milky Way and its dwarf galaxy companions.

"Without data from MAGIC, it would have been impossible to isolate this star among the hundreds of other stars in the vicinity of the Pictor II ultra-faint dwarf galaxy," Chiti said.

Chiti and colleagues combined MAGIC data with observations from the Very Large Telescope (VLT) in the Atacama Desert region of northern Chile and the Baade Magellan Telescope to discover low iron and calcium abundances of PicII-503, the lowest seen beyond our home galaxy. In turn, this revealed that PicII-503 was the first record of chemical enrichment found in a dwarf galaxy.

One possible explanation for the shockingly low iron-to-carbon ratio of PicII-503 is that when POP III stars went supernova, these explosions were relatively low in energy. That would have meant that while lighter elements like carbon were blasted into the interstellar medium, heavy elements like iron fell back into the wreckage of the supernova.

The fact that PicII-503 is found in one of the smallest dwarf galaxies ever seen, with a correspondingly low gravitational influence, supports the idea of POP III stars dying in low-energy supernovas.

"What excites me the most is that we have observed an outcome of the very initial element production in a primordial galaxy, which is a fundamental observation!” Chiti said. "It also cleanly connects to the signature that we have seen in the lowest-metallicity Milky Way halo stars, tying together their origins and the first-star-enriched nature of these objects."

The team's research was published on Monday (March 16) in the journal Nature Astronomy.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

Pablo Martinez Mirave is a Postdoctoral Fellow on Theoretical Particle Astrophysics at the Niels Bohr Institute, University of Copenhagen.

Imagine looking up at the night sky and seeing a star suddenly burst into a blaze of light brighter than anything nearby. A flash so bright that it briefly outshines an entire galaxy before fading forever.

This violent fate is rare: fewer than about 1% of stars are big enough to end their lives this way. Indeed, these dramatic explosions only occur in so-called "massive stars". These are stars with a mass roughly eight times or more that of the Sun.

But these cosmic explosions, known as supernovas, have naturally fascinated astronomers for centuries. In 1572, for instance, Danish astronomer Tycho Brahe observed a supernova explosion so bright that it could be seen with the naked eye for two years.

Yet what we can see with our eyes, or even with powerful telescopes, when these stars die, is only a tiny fraction of the story. Because most of the energy from a supernova is carried away by neutrinos, these are nearly invisible particles often called "ghost particles" because they pass through almost everything in their path.

Scientists are now finally on the verge of seeing these ghostly messengers. With the help of an extremely powerful telescope buried deep underground in Japan, astronomers may be able to catch a glimpse of these stellar "ghosts" – and with it the remnants of explosions from stars that died as long as 10 billion years ago.

Particles from before time

And there's a really good chance that scientists might be able to finally see these ghost particles this year. This is largely due to Japan's Super-Kamiokande telescope receiving an upgrade, which significantly enhances its ability to detect supernova neutrinos.

For me, as a particle astrophysicist, this would probably be one of the most exciting scientific achievements in my lifetime. Indeed, it would mean we could see particles that were produced even before the Earth itself existed, as the telescope is now sensitive enough to catch the faint "glow" of all the exploding stars in the universe.

This is all possible because neutrinos almost never interact with anything. They have no electric charge. So they can travel through space – and even through entire planets – without being absorbed or scattered, so almost nothing can stop them.

In fact, billions of these ghostly particles are passing through your body every second – and you don't even notice – and some of them have been travelling for more than 10 billion years to get here.

When a star dies

Big ideas lead to big questions, and one such question astrophysicists are trying to figure out is what remains after the explosion of such a star.

Does the collapsing core become a black hole? Or does it form a different type of star known as a neutron star, which then slowly cools over time? A neutron star is an incredibly dense object, only about 12 miles (20 kilometers) across, roughly the size of a large city or about the length of Manhattan.

If scientists are able to detect the combined signal from all the supernovae that have ever occurred, it would bring us closer to being able to answer these questions. It would also allow us to study the deaths of stars across the entire history of the universe, using particles that have been travelling toward us for billions of years without ever stopping.

Supernovas are rare in our galaxy, happening only once every few decades. But across the universe, a massive star explodes in a supernova roughly once every second. When they explode, they release enormous energy: only about 1% is visible light, while 99% escapes as neutrinos.

Even though these neutrinos are almost invisible, they carry the story of every star that has ever exploded – and now, for the first time, we may be able to catch them.

So if 2026 does bring the first clear detection, it will mark a new era in astronomy. For the first time, we won’t just observe the brilliant explosions of nearby stars, but the collective story of all the massive stars that have ever lived and died.

And it all starts with a telescope buried deep underground in Japan, patiently watching for the faint, ghostly glow of the universe’s oldest explosions.

We could soon be able to "see" inside a neutron star and learn what extreme matter governed by exotic physics lurks there, thanks to the imprint of tidal interactions on gravitational waves emitted by pairs of neutron stars spiraling toward an explosive merger.

"One hope is that we'll be able to get some information about the neutron-star equation of state at densities found in the inner core of a neutron star," said Nicolás Yunes of the University of Illinois, who led the research, in a statement. "Is there really a quark core, as some have recently claimed? Are there phase transitions occurring inside that we don't know about yet?"

A neutron star is the compact remnant of a massive star that has gone supernova. With a diameter about the same as a large city, yet packing a mass several times that of our sun, neutron stars are incredibly dense. The pressure in their interior is so great that atoms are crushed and split apart into their constituent particles. The positively charged protons and negatively charged electrons are smushed together, forming a soup of neutral neutrons, which is why we call these objects neutron stars.

However, deeper down inside a neutron star, close to its core, things could be even weirder. The gravitational pressure could be so extreme as to crush neutrons into their building blocks, which are fundamental particles called quarks and the gluons that ordinarily bind quarks together to form protons and neutrons.

Scientists call this state of matter a quark-gluon plasma. This state of matter existed during the first fraction of a second after the Big Bang, and outside of particle accelerator experiments, the only other location in the universe where quark-gluon plasma may exist is inside neutron stars.

If scientists could understand the interior of neutron stars, they could therefore learn more about the state of matter immediately after the Big Bang.

Binary neutron stars have long been considered the best bet for deciphering what lurks within. These pairs of neutron stars spiral around one another in elliptical orbits, inching ever closer until they collide and merge in a kilonova. Crucially, their in-spiral sees the release of gravitational waves.

Now, scientists led by Yunes and Abhishek Hegade of Princeton University think they've figured out how to decipher the frequency of these gravitational waves to interpret the interior structure of neutron stars.

"As they get closer, tidal forces from one [neutron] star begin to deform the other and vice versa," said Hegade. "The amount of deformation depends on what's inside of those stars."

The problem is that the extreme gravity and high velocity (up to 40% the speed of light) of the neutron stars as they spin about one another means that scientists have to look toward Albert Einstein's general theory of relativity for solutions. This is a complex endeavor, but Yunes and Hegade think they now have the answer.

As the binary neutron stars deform the shape and structure of each other through their gravitational tides, they trigger oscillations within their interior, like the ringing of a bell. The patterns of these oscillations are called modes, and the frequency of these modes is imprinted on the gravitational waves that the binary neutron stars radiate away.

A full set of modes is required to understand the binary system. Discerning these modes, however, is complicated by the fact that the tidal forces are dynamical: they change as the neutron stars orbit one another, and the effects of each neutron star overlap, making distinguishing what's going on even more difficult.

"Without a complete set of modes, it's entirely possible that you could miss part of the tidal response when you model it, as there could possibly be other pieces you're omitting from the response's mathematical description needed to capture all the physics," said Yunes.

Newtonian physics — that is, the basic physics of gravity according to Isaac Newton's law of gravitation — contains a full set of oscillating modes for a regular object. These modes are referred to as a damped harmonic oscillator. However, in relativistic physics, it has not been clear whether all the modes could be derived. For example, gravitational waves that radiate away energy from binary neutron stars are a phenomenon of general relativity, which succeeded Newtonian gravity, and as such they are not considered by Newtonian physics.

"If your system is losing energy, then its modes cannot be complete," said Hegade.

The solution was to break the problem down, considering each neutron star individually, and its companion as just a source of gravitational tides. Yunes' and Hegade's team then divided each neutron star into separate regions of varying gravitational strength at different scales, describing strong gravity and weaker gravity. They found approximate solutions for each scale, and then combined them. They even found that the loss of energy from gravitational waves effectively cancelled out. This allowed them to derive a solution describing all the oscillatory modes of a neutron star's interior, and furthermore, how these modes would be imprinted on the frequency of the resulting gravitational waves.

"We showed two major things," said Hegade. "First, we were able to subtract off radiation, finding that a neutron star's modes do indeed form a complete set. Second, we found that if you consistently solve a certain set of equations using a tidal field that's sufficiently 'smooth,' it's a solution to the interior of a star, and you can do all the same things in general relativity as in Newtonian gravity."

This isn't the end of the story. The work of Yunes' and Hegade's team is purely theoretical at this stage, and current gravitational-wave detectors are not sensitive enough at higher frequencies to detect this imprint. However, Yunes and Hegade are optimistic that the next generation of detectors will do the trick.

The findings were published on Feb. 18 in the journal Physical Review Letters.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

Vahe Peroomian is a Professor of Physics and Astronomy at the USC Dornsife College of Letters, Arts and Sciences.

As a space scientist, every time I go outside with my family, I tell my children to look up at the sky. The front door of our home looks southeast, and on winter nights the constellation Orion hangs majestically just above the horizon as soon as it grows dark enough to see stars.

One summer night, my son came running in and exclaimed, "Dad, Orion's not there!" It was time for his first real astronomy lesson.

We went outside and I asked him to find the Big Dipper, the easily identifiable pattern of stars that make up a portion of the constellation Ursa Major. I reminded him that we could always see the Big Dipper no matter what time of the year it was.

So, why is it that Orion is not always visible in the night sky, and certainly not in the same location month after month, while the Big Dipper always is? The answer is intimately tied to a few concepts: how astronomers measure the length of a day, the motion of the Earth around the sun during a year, and the cadence with which stars rise and set night after night.

Sidereal time

If you look eastward at the same hour for two nights in a row, you’ll find that the stars seem to be in the same place. But they’re not, and this movement becomes apparent if you continue observing at the same hour for a week or more. A combination of the Earth’s daily rotation on its axis and its yearly orbit around the Sun cause them to appear to move across the sky.

Earth spins on its axis, which runs from the South Pole through the center of the Earth to the North Pole, once a day. Astronomers measure a day in two different ways: They measure a solar day, 24 hours long, with the position of the sun from high noon to high noon. They measure a sidereal day with respect to distant stars that are fixed in the sky. A sidereal day is 23 hours and 56 minutes long.

The constellation Orion – and every star in the night sky – will appear in exactly the same place every 23 hours and 56 minutes. Because of this slight offset, stars will appear to rise four minutes earlier every 24 hours on successive nights. Over the course of a month, a star that was close to the eastern horizon at 10 p.m. will now be much higher in the sky, having risen two hours earlier.

So while the constellation Orion appears close to the horizon at sunset in late December, it is nearly overhead in February and March.

You can use an interactive star chart to see this phenomenon. Do you want to find Orion in August in North America? Just wake up at 4:30 a.m. and look eastward.

Unlike Orion, the Big Dipper is always visible at night in most of the Northern Hemisphere. This is because of how Earth’s daily rotation is projected onto the stars.

Circumpolar stars

Astronomers use a common set of reference points to project Earth's north and south poles, and the equator, onto the celestial sphere, an imaginary sphere encompassing the sky.

The idea of the celestial sphere evolved in ancient times from the notion that the Earth was the unmoving center of the universe. The projection of Earth's equator delineates the celestial equator, and the poles project onto the north and south celestial poles.

The motion of stars near the celestial poles differs from how Orion and other constellations behave. Presently, the north celestial pole is very close to the star Polaris, also known as the North Star. Stars close to Polaris never rise or set. They appear to circle counterclockwise around that star as the Earth spins on its rotation axis once a day.

The number of these circumpolar stars increases as you move toward the North Pole. There are no circumpolar stars at the equator. Every star and constellation rises in the east and sets in the west because Earth rotates west to east on its axis.

If you are standing at the North Pole, every northern constellation is circumpolar, circling the North Star and never rising or setting. The pattern is similar in the Southern Hemisphere, with the southern constellations circling clockwise around the south celestial pole.

Earth's precession

Millennia ago, people charted the path of the Sun through the constellations of the zodiac, which birthed the practice of astrology.

What does it mean for the sun to be in Sagittarius, for example? It means that to see the constellation Sagittarius, you have to be looking toward the sun. That would make it daytime, when the stars are not visible. Wait for nightfall, and you can see Gemini high in the sky. Six months later, the sun is in Gemini, and Sagittarius is visible in the night sky. This pattern repeats year after year, as the Earth orbits the sun. Your zodiac signs depend on which constellation the sun was in when you were born.

There is one other change in the night sky that occurs on time scales much longer than a human lifetime. Because of the gravitational influence of the sun, and to a lesser extent Jupiter, on Earth's daily rotation, Earth's spin axis precesses, or moves in a circle, like a toy top spun on a table.

Because of this motion, which also subtly changes Earth's orbit in space, Polaris will no longer be the North Star a thousand years from now. Wait 12,000 years, and the bright star Vega will be closest to the north celestial pole, more than 50 degrees across the night sky from its present location near Polaris.

Another consequence of this motion, sometimes referred to as the precession of the equinoxes, is that today the constellations of the zodiac no longer align with the traditional dates associated with them.

For example, when horoscopes and astrological signs were originally devised, the sun was in the constellation Sagittarius from Nov. 22 to Dec. 21. However, because of precession over thousands of years, the sun now crosses this constellation from Dec. 18 to Jan. 19. It spends the early part of December in Ophiuchus, which is not part of the traditional 12 constellations of the zodiac.

These changes in the night sky take weeks, months or even hundreds of years to be visible. If you’re not that patient, you can fly to the opposite hemisphere to see Orion upside down and the night sky turning in the opposite direction above.

Astronomers have tracked a powerful blast of radiation called a gamma-ray burst (GRB) back to its source, finding a collision between extreme stellar remnants called neutron stars within colliding galaxies. This could reveal more about these extraordinary collisions, thought to be the only events in the universe capable of generating heavy elements like the gold and silver we wear on our fingers and around our necks.

The GRB, designated GRB 230906A, was spotted on Sept. 23, 2023, by an array of NASA space telescopes, including the Chandra X-ray Observatory, the Fermi Gamma-ray Space Telescope, the Neil Gehrels Swift Observatory, and the Hubble Space Telescope. GRB 230906A was tracked back to a neutron star merger within a tiny galaxy that is itself embedded in a river of gas 600,000 light-years long, or about six times as long as the width of our entire galaxy.

Previously, collisions between neutron stars, which are born when massive stars run out of fuel for nuclear fusion and "die" in supernova explosions, had only been observed in medium to large galaxies. Thus, these results show that these merger events between extreme dead stars can occur in more diminutive galaxies

"Finding a neutron star collision where we did is game-changing," discovery team-leader Simone Dichiara of Penn State University said in a statement. "It may be the key to unlocking not one, but two important questions in astrophysics."

The first conundrum Dichiara refers to, which could be solved by a neutron star merger in an unprecedented location, is the fact that when astronomers trace GRBs back to their points of origin, they often seem to occur away from dense galactic cores where collisions should be more common, and sometimes away from galaxies altogether.

The other puzzle relates to the fact that, though neutron star collisions are believed to generate the only environments violent and turbulent enough to forge elements heavier than iron, like gold, silver, and platinum, these elements are often detected in stars that lie far from galactic centers and which should have formed before it was possible to be enriched with such heavy elements.

'A collision within a collision'

This neutron star collision was initially detected via GRB 230906A by Fermi, with astronomers then precisely pinpointing the location where the merger occurred using Chandra, Swift, and Hubble.

"Chandra's pinpoint X-ray localization made this study possible," team member Brendan O’Connor, of Carnegie Mellon University, said. "Without it, we couldn't have tied the burst to any specific source. And once Chandra told us exactly where to look, Hubble's extraordinary sensitivity revealed the tiny, extremely faint galaxy at that position. We were only able to make this discovery after we put all the pieces together."

The stream of gas within which the team discovered the home galaxy of this merger is thought to have been created when a group of galaxies collided hundreds of millions of years ago. This event stripped gas and dust from these galaxies, forming a gas stream and leaving to drift in intergalactic space.

"We found a collision within a collision," team member Eleonora Troja of the University of Rome in Italy said. "The galaxy collision triggered a wave of star formation that, over hundreds of millions of years, led to the birth and eventual collision of these neutron stars."

The discovery hints that some GRBs appear to originate from beyond the limits of galaxies because their points of origin are actually tiny galaxies that are too faint to be seen.

As for the heavy element enrichment of stars that dwell far from the galactic center, the team theorizes highly explosive neutron star mergers like the one that launched GRB 230906A could not only forge such elements but could also disperse them to the very edge of galaxies.

The team's research is set to appear in the Astrophysical Journal Letters.

Astronomers have witnessed the birth of a rapidly spinning, highly magnetized neutron star or "magnetar" for the first time.

The observation of this event, triggered by the death of a massive star, confirms the link between the creation of magnetars and super-bright supernova explosions. These superluminous supernovas can be as much as ten times brighter and last much longer than the typical supernova explosions that occur when massive stars run out of nuclear fuel and undergo gravitational collapse, or "core collapse," to birth neutron stars or black holes.

Almost since they were first discovered in the early 2000s, scientists have theorized that the birth of magnetars, which have the most powerful magnetic fields in the known universe, are connected to superluminous supernovas, but the smoking gun confirmation of this connection was missing.

"What's really exciting is that this is definitive evidence for a magnetar forming as the result of a superluminous supernova core collapse," team member Alex Filippenko of the University of California, Berkeley, said in a statement.

The magic trick behind super-supernovas

The theory connecting magnetars and superluminous supernovas was first suggested by Dan Kasen and Lars Bildsten of UC Berkeley and independently by Stanford Woosley of UC Santa Cruz. It suggests that when a star that possesses a powerful magnetic field and that is around 25 times the mass of the sun collapses, its magnetic field intensifies. The result is a magnetar with a magnetic field 100 to 1,000 times as strong as the magnetic field of a "standard" neutron star.

The collapse of the core of a massive star to a width of around 12 miles (20 kilometers) has another consequence. Just as an ice skater at the Winter Olympics draws in their arms to increase their spin speed, the rapid decrease in diameter of a neutron star speeds up its rotation.

As a result, some newborn neutron stars can spin at a rate of 700 times a second or more. These objects can blast beams of radiation from their poles that sweep across the universe like light from a cosmic lighthouse. In these cases, neutron stars and magnetars are referred to as pulsars.

As magnetars spin rapidly, their rotating magnetic fields accelerate particles and then fire them out into material shed by the progenitor star during their supernova death. That causes this debris to increase in brightness.

The team behind this research confirmed this connection when they analysed data from a supernova spotted in 2024 and designated SN 2024afav. This investigation revealed strange "chirps" in the light curve from this supernova, which are indicative of general relativistic effects caused by a magnetar.

"The basis of Dan Kasen and Stan Woosley's model is that all you need is the energy of the magnetar deep within, and a good fraction of it will get absorbed, and that'll explain why the thing is superluminous," Filippenko said. "What had not been demonstrated was that a magnetar did in fact form in the middle of the supernova."

The researcher added that this is what this research, published on Wednesday (March 11) in the journal Nature, finally demonstrates.

"For years, the magnetar idea has felt almost like a theorist's magic trick — hiding a powerful engine behind layers of supernova debris. It was a natural explanation for the extraordinary brightness of these explosions, but we couldn't see it directly," Kasen said. "The chirp in this supernova signal is like that engine pulling back the curtain and revealing that it's really there."

The supernova smoking gun

First spotted by the 27-telescope network of the Las Cumbres Observatory in Dec. 2024, the brightness of SN 2024afav was tracked by astronomers for 200 days. What the team noticed was that this supernova, which occurred around 1 billion light-years from Earth, didn't gradually fade after like a typical supernova.

After peaking at the 50-day mark, the brightness of SN 2024afav gradually oscillated downward, with a series of four noticeable "bumps" in brightness that resemble a sound increasing in frequency. Hence, these features were labelled chirps.

Similar bumps have been seen in the light curves of other supernovas, with scientists linking them to shocks rippling out from the central stellar body and striking previously ejected material. However, no previous supernova had demonstrated as many as four of these chirps.

This team theorizes that material from the explosion seen as SN 2024afav actually fell back to the central magnetar after it was ejected, forming a swirling flattened cloud called an accretion disk around this powerful stellar remnant.

Because material ejected in the supernova is unlikely to be symmetric, the accretion disk is also unlikely to be symmetric. That leads to the axis of spin of the magnetar and that of the accretion disk being misaligned.

Einstein's theory of gravity, known as general relativity, suggests that as objects of great mass spin, they drag the very fabric of space along with them, a process called "frame-dragging" or the Lense-Thirring effect. This effect would cause the accretion disk to wobble, and a wobbling accretion disk would occasionally block light from the magnetar and occasionally reflect it. This creates a strobing effect that turns the entire system into a cosmic "lighthouse."

As the disk contracts and falls to the magnetar, the rate of this wobbling increases, and that generates the chirps seen in the light curve of SN 2024afav.

"We tested several ideas, including purely Newtonian effects and precession driven by the magnetar's magnetic fields, but only Lense-Thirring precession matched the timing perfectly," lead author of the paper, Joseph Farah of UC Berkeley, said. "It is the first time general relativity has been needed to describe the mechanics of a supernova."

The team was also able to determine that this central object is spinning around 238 times every second and has a magnetic field around 300 trillion times more powerful than Earth's magnetosphere, confirming this as a magnetar. That's the smoking gun astronomers have been looking for to connect magnetars and superluminous supernovas.

"He [lead author Joseph Farah] has tied the bumps into the magnetar model and explained everything with the best-tested theory in astrophysics — general relativity. It is incredibly elegant." Filippenko added. "To see a clear effect of Einstein's general theory of relativity is always exciting, but seeing it for the first time in a supernova is especially rewarding."

Our sun and a host of sun-like "solar twins" may have migrated away from the core of the Milky Way galaxy together, potentially making the solar system more hospitable to life as we know it, new research finds.

Around the Milky Way are solar twins, stars that physically appear very similar to the sun. By analyzing solar twins, astronomers hope they can learn more about the history of the sun.

In two new studies, researchers examined data from the European Space Agency's Gaia satellite, which captured data about two billion stars to create the most precise 3D map of the Milky Way ever made. They focused on 6,594 solar twins within about 1,000 light-years of Earth. This collection of solar twins is about 30 times larger than previous surveys of these stars.

"We found many more solar twins with ages similar to the sun than I had expected," researcher Daisuke Taniguchi, an astronomer at Tokyo Metropolitan University, told Space.com.

By analyzing the sizes, temperatures and compositions of these nearby solar twins, Taniguchi, Takuji Tsujimoto at the National Astronomical Observatory of Japan and their colleagues were able to estimate the stars' ages. Looking at the range of ages, they noticed a broad peak for 1,551 stars about four billion to six billion years old. (This population includes our sun, which is about 4.6 billion years old.)

The discovery that the sun and many of these solar twins are of similar ages and located about the same distance from the center of the galaxy suggests that the sun is not at its current position by accident. Previous research suggested that, based on the sun's "metallicity" — its levels of elements heavier than hydrogen and helium — it was born more than 10,000 light-years closer to the galaxy's inner regions, which are higher in metals than the part of the galaxy in which the sun now resides.

The new results suggest the sun may be a part of a larger population of stars that migrated outward from the galactic core at about the same time — four billion to six billion years ago.

"We are learning about the sun's past trajectory indirectly by studying other, similar stars," Taniguchi said.

This discovery sheds light not only on the nature of our solar system, but the evolution of the galaxy itself. At the center of the Milky Way is a giant rotating bar-like structure that would now make it difficult for such a mass migration of stars to occur. However, these new findings reveal details about when this "co-rotation bar" formed. Indeed, the birth of this enormous sweeping bar may have initially concentrated gas to help trigger star formation and then propel stars outward, the researchers suggested.

These new findings might also shed light on what conditions may have helped life on Earth to evolve, the researchers said.

"The inner regions of the Milky Way are thought to be more hostile environments for life, with energetic events such as supernova explosions occurring more frequently," Taniguchi said. If the sun migrated outward relatively soon after its birth, "the solar system may have spent most of its history in the quieter outer disk. In other words, the sun may not have arrived in a life-friendly environment purely by chance, but rather as a consequence of the formation of the galactic bar."

The scientists aim to expand their work to cover a larger release of data from Gaia planned for December. They also plan to look more closely at the compositions of these solar twins, which "may help identify stars that were born in the same place and at the same time as the sun — that is, true twins," Taniguchi said.

The scientists detailed their findings March 12 in two studies in the journal Astronomy & Astrophysics.

A new image captured by the European Southern Observatory's (ESO) Very Large Telescope (VLT) is helping astronomers discover a new cloud of gas orbiting the supermassive black hole at the heart of our Milky Way galaxy.

What is it?

This image offers a new view of the center of the Milky Way galaxy, where the supermassive black hole Sagittarius A* (or Sgr A*) resides. In the image, a dense cluster of stars and gas can be seen orbiting Sgr A*. Two clouds of gas known as G1 and G2 had been previously observed orbiting our galaxy's black hole, but astronomers believe this image helps reveal the existence of a third cloud known as G2t.

The three clouds of gas likely originate from the same pair of massive stars, known as IRS16SW. "As IRS16SW moves around the black hole, each cloud of gas is ejected in a slightly different orbit, explaining the small differences in the trajectories of the 'G-triplet'", ESO wrote in a statement accompanying the image.

Why is it amazing?

Like all black holes, astronomers can't directly observe Sgr A* because even light can't escape its gravitational pull. However, in 2022, scientists managed to capture an image of light, in the form of radio waves, from hot gases swirling around the edge of Sgr A*.

Observations of features like G2t are helping astronomers get a better glimpse at the "invisible giant" at the core of our cosmic home. "This discovery shows that, despite decades of monitoring our Milky Way center, new unanswered curiosities still arise," the ESO wrote in the statement accompanying the image.

"But what could be more exciting than mysteries waiting to be solved?"

Using NASA's exoplanet-hunting spacecraft TESS (Transiting Exoplanet Survey Satellite) astronomers have discovered an extraordinary quadruple star. The system is the tightest 3+1-star system, a subset of quadruple star systems, yet discovered. Excitingly, the discoverers of this system were also able to determine what its final fate will be.

The system TIC 120362137 consists of a stable and tightly bound inner system of three stars orbiting each other that are orbited by a more distant outer star observing the system from afar. While the outer star is located at around the same distance from the stellar triplet as the distance from Jupiter to the sun, the inner stellar sub-system would fit within the orbit of Mercury, the closest planet to the sun, around our star.

TIC 120362137 is an important discovery for researchers because, in addition to 3+1 systems being extremely rare — as a so-called hierarchical star system, where several stars orbit each other within a relatively small area — TIC 120362137 could also help us better understand stellar formation and long‑term orbital stability.

"TIC 120362137 is currently the most compact known 3+1-type quadruple star system," team leader Tamás Borkovits, a researcher at the University of Szeged, Hungary, told Space.com.

The extraordinary nature of this system wasn't immediately obvious, however.

"By a simple inspection of the early TESS data, we realized that TIC 120362137 is a compact, tight, triply eclipsing triple star system," Borkovits said. The researcher added that when the team first saw TIC 120362137, the hitherto unknown system initially seemed to consist of a pair of stars eclipsing each other every 3.3 Earth-days, creating a drop in brightness lasting between one and two hours.

"We know thousands of such systems, called eclipsing binaries. Therefore, there was nothing interesting or peculiar at that stage," he continued. "Then, we realized that there are extra one-to-two-day-long fadings every 25 to 26 days, which made it clear that there must be a third star also in the system, with an orbital period of around 51 days. Therefore, we found that TIC 120362137 must be a triply eclipsing triple system.

"However, we still did not know about the fourth star at that moment."

The team then saw further eclipses, indicating a fourth star, the presence of which was confirmed using the Tillinghast Reflector Echelle Spectrograph (TRES) on the 1.5-meter Tillinghast telescope located on Mt. Hopkins in Arizona.

"TIC 120362137 is a record-holder in the sense that we found that the outermost star has an orbital period of only around 1,046 days, which is the shortest amongst all the currently known 3+1 quadruple stars by far," Borkovits said. "The discovery of such systems, however, is very, very difficult. To discover a fourth, most distant component by checking eclipses in the same way as the inner system requires much more time, maybe even several decades or longer. Other kinds of detection of a fourth star may happen, but only serendipitously."

The team was able to determine other characteristics of the stars in this system, too. The scientists found the three innermost stars are more massive and hotter than the sun, while the outermost component, the fourth star, is cooler, less massive and thus similar to the sun. Additionally, by using computer simulations, the researchers were able to determine the future of this 3+1 star system, ending up as just two white dwarf stellar remnants.

"First, the most massive star, which is the primary component of the innermost binary, will reach the red giant state. In that state, it will merge with its mate, the secondary star of the innermost binary. We call this daughter stellar body A'," Borkovits said. "Then, in around 276 million years, in a second step, this new, merged star A' will merge with the third stellar component, star B, when both stars have reached the red giant stage. We call this massive new star AB."

He added that, following this, the star AB will lose a significant part of its mass, eventually collapsing to form a white dwarf. As this happens, the distant fourth star will undergo a similar process, creating the second white dwarf.

"Finally, therefore, our evolutionary model predicts the binary of these two white dwarfs with an orbital period of around 44 days," Borkovits said. "The more massive white dwarf with a mass of around 89% the mass of the sun is formed after two mergers involving the three inner stars, while the less massive white dwarf, with a mass around 29% that of the sun, is simply formed from the fourth, most distant star.

The team's results were published on Tuesday (March 3) in the journal Nature Communications.

Editor's Note (03/06/26): Journal source was updated from "Nature" to "Nature Communications."

Many astronomical objects play by clear rules and fit into neat categories, but brown dwarfs (celestial objects too massive to be mere planets, but too small to be real stars) continue to refuse to cooperate.

Astronomers recently studied a sample of 70 objects, ranging from Jupiter-mass planets to brown dwarfs that are right on the brink of stardom. By looking for a relationship between the mass of these objects and certain features of their star systems (like whether the host star contained elements heavier than helium, or how round the objects' orbits were), the researchers hoped to draw a clear line that divides massive objects that form like stars and smaller ones that form like planets. But they were destined for disappointment, because the actual universe is messy and complicated.

As it turns out, the line between stars and planets might be more of a gray, fuzzy continuum, according to University of California Los Angeles astrophysicist Gregory Gilbert and his colleagues in a recent paper published in The Astronomical Journal.

Planets and stars form differently — except for that group in the middle

Stars, by definition, boast at least 80 times the mass of Jupiter, and they form from the outside in. When a clump of gas in a molecular cloud collapses under its own gravity, the densely-packed atoms at its core start fusing together, releasing heat and light; a star is born.

Giant gas planets of sizes up to about Jupiter's mass, on the other hand, form from the inside out. First, a few grains of dust clump together in the disk of material around a newborn star, and their combined gravity is enough to start attracting even more dust. Material keeps piling on, faster and faster, building up a rocky core surrounded by thick layers of gas.

In between, however, there's a whole slew of objects that astronomers aren't sure whether to classify as "failed stars" or "overgrown planets."

At between 13 and 80 times the mass of Jupiter, brown dwarfs aren't quite massive enough to fuse hydrogen into helium like a real star, but they're just big enough to fuse deuterium, an isotope of hydrogen that includes a neutron along with the standard proton and electrons. (Weirdly, deuterium requires less pressure to fuse into helium than straight hydrogen does.) And then there are "sub-brown dwarfs," gas giants which are truly gargantuan by planet standards, but they're not quite large enough to be proper brown dwarfs.

Ideally, there should be a clear line: objects above a certain mass should be failed stars that formed from collapsing gas clouds, and objects below that mass should be overgrown planets that coalesced from planetary disks.

So far, though, astronomers haven't had much luck finding any such line.

In 2024, astrophysicist Steven Giacalone, one of the coauthors of the current study, found a brown dwarf that seemed to have formed by core accretion, making it basically the biggest planet ever. And some sub-brown dwarfs — gargantuan planets not quite big enough to count as brown dwarfs — seem to have formed by gravitational collapse, which means they failed so hard at being stars that they couldn't even make it as brown dwarfs.

"Exactly how large of an object can be formed by core accretion or how small of an object can be formed by disk instability or cloud fragmentation remains to be determined," wrote Gilbert and his colleagues in their recent paper.

"Perhaps … we have not yet examined the right combination of parameters"

Gilbert and his colleagues used statistical models to test how their objects' mass related to the chemical makeup of the host stars and the shape of the objects' orbits.

Looking at these objects' orbital eccentricity (a measure of how close to a perfect circle an orbit is) tells pretty much the same story. Less massive objects tend to have rounder orbits, while the most massive, brown-dwarf-like of these objects vary more in their eccentricity. However, Gilbert and his colleagues noted that the trend was very gradual.

"We may reasonably assume that as the mass of an object increases, the likelihood that it formed via core accretion drops and the likelihood that it formed by gravitational instability [a gas cloud collapsing in on itself] rises," the researchers wrote in their recent paper, but it's more of a spectrum than a clean sorting of objects into two groups.

And then there's metallicity. A planet can only accrete enough material, quickly enough, to grow into a gas giant if it forms in a star system that's very metallic — meaning that it's chock-full of elements heavier than helium (mostly carbon, oxygen, and iron). So if there were a clear dividing line between more massive objects formed by collapsing molecular clouds and less massive objects formed by accretion, researchers like Gilbert and his colleagues would expect to see smaller sub-brown dwarfs forming only in metal-rich star systems. But that's not what Gilbert and his colleagues actually saw in their data.

Instead, it seems that there's no relationship between the mass of a gas supergiant and its star system's metallicity. That suggests that some of these objects formed by core accretion, while others formed more like stars — with the same end result and, often, the same mass. Which means right now, we can't tell by looking whether something is a failed star or a wildly successful planet.

"Perhaps a clear dividing line between formation channels does exist, but we have not found it yet, either because we do not have enough objects or because we have not yet examined the right combination of parameters," wrote Gilbert and his colleagues in their recent paper.