I used to think Uranus was the sort of planet you graduated into. Saturn and its rings first, obviously. Jupiter and its cloud bands soon after that. Venus, if it's shrinking to a crescent (which it soon will be), and, of course, Mars and its ice caps. But Uranus? The seventh planet feels like something reserved for people with huge telescopes, expensive eyepieces and incredibly lucky atmospheric seeing. It may be considered an ice giant planet, but it's almost four times farther from the sun than Jupiter and twice as far as Saturn — and it's a lot smaller than both. Uranus didn't figure in my plans.

And yet on a frosty evening in September, a few years ago, I finally got to see it as a blue-green dot nearly 1.8 billion miles away. It was through a large Dobsonian telescope belonging to one very generous member of the Salt Lake Astronomical Society, outside the visitor center at Bryce Canyon National Park, which hosts popular astronomy and night-sky programs. Uranus shone dimly, but I could easily make out its color by averting my eyes (looking slightly to the side of the planet rather than directly at it). That way, the human eye's light-sensitive peripheral cells can catch brightness — it's a technique that's worth learning for all kinds of telescopic astronomy. Even then, Uranus looked like a faint, motionless star rather than a glowing planet. It was no Saturn.

What surprised me wasn't finally seeing Uranus — that was down to a massive telescope. It was how suddenly my perception changed once my eye locked onto it. After seeing it up close (ish), I wanted to know exactly where Uranus was in the night sky. Uranus is technically visible to the naked eye, but it is very challenging to see. It shines at 5.7 magnitude — right at the absolute limit of human visibility, but in Bryce Canyon's dark moonless skies, it was definitely there. Was it a satisfying sight? Not especially — but I could not unsee it. That transition — from looking casually to carefully observing, first with powerful optics and then navigating with the naked eye — is what observational astronomy is all about. Uranus now always figures in my plans, but typically only when I have access to a very large telescope.

Finally seeing Uranus is a milestone. Most people remember their first view of Saturn because its rings impress immediately. But many people remember Uranus because they had to work for it. It's a planet you can discover for yourself — and you can do it this week.

What's happening and when to look

I tend to forget all about Uranus unless it's involved in a conjunction — and that's exactly what's happening. Conjunctions involving Uranus tend to occur a couple of times each year, typically as one of the fast-moving, closer planets — such as Venus and Mars — appear next to it. Venus was close to Uranus back in April, and on July 4, it's the turn of Mars. A conjunction between Mars and Uranus happens about every two years as the red planet surges past on its far quicker journey around the sun (687 Earth days versus the 84 years it takes Uranus).

This won't be the most convenient conjunction to observe, but they'll get to within about 11 arc minutes of each other — extremely close! From the northern hemisphere, the planets will be low on the eastern horizon in the early morning hours before astronomical dawn. The best time to be up and looking east will be about 3:45 a.m. local time. The observing window is only about 45 minutes before dawn, making it harder to find with every passing minute.

How and when I'm watching it

Find Mars, find Uranus. That's the entire point of using a close conjunction to see the seventh planet. Mars will serve as a guidepost and be easy to see. It will shine at 1.3 magnitude below the sparkling Pleiades open cluster. You won't be able to miss it in a clear sky. All you have to do is look slightly above Mars for Uranus — first with the naked eye, then with any pair of binoculars (I'll be using 10x50 binoculars). The conjunction will be close enough to fit comfortably in binoculars and to look beautiful in a small telescope, if you have one.

Normally, locating Uranus involves hopping through fairly anonymous star fields while constantly second-guessing whether you are looking at a star or the planet itself. Here, Mars does the navigation for you. Your reward will be the sight of a tiny pale point with a subtle blue-green tint. The satisfaction comes less from appearance and more from seeing something so distant directly with your own eyes.

There's also something fitting about this conjunction falling on July 4 during the 250th anniversary year in the U.S. Uranus takes 84 years to orbit the sun, meaning it has completed almost exactly three orbits since the Declaration of Independence was signed in 1776. The planet itself was not discovered until 1781, when William Herschel identified it while searching the sky systematically rather than casually. It's a reminder that back in 1776, only six planets were known about. Now we're on a hunt for a ninth planet (sorry, Pluto).

Stargazer's corner: July 3-9, 2026

July opens with a slowly darkening sky after the long twilight of late June. Earth reaches aphelion on July 6, its farthest point from the sun (the seasons are driven by Earth's tilted axis, not its distance from the sun). So the sun's disk will be at its smallest in the sky, one factor contributing to the total solar eclipse on Aug. 12. Meanwhile, the very early hours of July 7 and 8 will see a close conjunction of a last quarter moon and Saturn in the east, kicking off relatively moonless conditions for the following 10 nights or so.

Asterism of the week: Summer Triangle

By early July, the Summer Triangle dominates the sky after dark. Formed by Vega, high overhead, Deneb to the northeast and Altair lower in the south, it creates a vast, unmistakable pattern that defines the season. It's actually not a constellation, but an asterism — a popular shape in the sky, like the Big Dipper — and its scale is what makes it so useful. Once you've got it nailed, it becomes a framework for the entire sky, helping you orient yourself instantly all season long. It also traces the path of the Milky Way, which runs straight through it, adding an extra sight if you're somewhere not blighted by light pollution.

Want to see Uranus for yourself? Independence Day morning offers one of the best opportunities in decades, as the distant ice giant passes extraordinarily close to Mars in the predawn sky.

Although we often hear that only five planets are visible to the unaided eye, Uranus can also be seen from Earth under the right conditions. As the seventh planet from the sun, it is very faint — near the threshold of naked-eye visibility at roughly sixth magnitude — so viewing it requires a very dark sky with little to no significant light pollution.

The second challenge is knowing exactly where to look. Uranus is faint enough to blend into a background of similarly dim stars, but early on Saturday, July 4, at around 4 a.m. local daylight time, Mars provides a useful guide. On that Independence Day morning, Mars and Uranus will appear unusually close together in the sky.

Finding Mars first

Mars currently rises about half an hour before the first light of dawn. It is still relatively faint at about magnitude +1.3, and through a telescope it appears tiny, measuring less than 4.5 arc seconds across. Look for it low in the east-northeast, about 5.5 degrees directly below the Pleiades star cluster.

• Find Mars low in the east-northeast before dawn.
• Point binoculars or a small telescope at Mars.
• Look almost directly above Mars for a much fainter, star-like point of light. That will be Uranus.

What Uranus will look like

Uranus should resemble a tiny greenish star and will appear only about 1/63 as bright as Mars. Although Uranus is nearly 7.5 times larger than Mars, it is more than 9.5 times farther away as seen from Earth. At about 1.88 billion miles (3.02 billion km), it appears only slightly smaller than Mars in apparent size, measuring about 3.5 arc seconds across.

How close will they be?

According to Belgian celestial calculator Jean Meeus, Mars and Uranus will be closest at 5 a.m. Universal Time (UTC) on July 4, when only 6 arc minutes will separate them. For comparison, Mizar — the middle star in the Big Dipper's handle — and its fainter companion Alcor are separated by about 12 arc minutes. In other words, Mars and Uranus will appear only half as far apart as Mizar and Alcor.

Observers with exceptionally sharp vision and very dark skies may want to try spotting Uranus near Mars without optical aid, though binoculars or a small telescope will make the view much easier.

Mars and Uranus are in conjunction on average once every 2.38 years. But meetings as close as this one are quite rare, occurring on average once about every 40 years. The next similarly close approach between these two worlds that is readily visible in a dark sky is not due until Dec. 8, 2147!

A Bonus Target: HIP 19146

If you are using a small telescope, look for an even fainter object about 2 arc minutes below Uranus. This is not a Uranian satellite, but a background star cataloged as HIP 19146. The "HIP" designation comes from Hipparcos; a European Space Agency satellite launched in 1989 and operated until 1993. Hipparcos was the first space mission devoted to precision astrometry, the accurate measurement of celestial positions and distances.

On the morning of the upcoming Mars-Uranus conjunction, try to spot this eighth-magnitude star as well. It is about 11 times dimmer than Uranus and lies roughly 882 light-years from Earth.

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.

For years, astronomers have suspected that our solar system may have lost at least one world at some point in its 4.5-billion-year history. And now, new research suggests the moons of Jupiter and Uranus may indeed hint that our planetary neighborhood once had a third ice giant.

Evidence has shown that between 3 billion and 4 billion years ago, the solar system's largest planets likely orbited much closer to the sun (and to each other) than they do today. It's also suggested that our four giant planets — Jupiter, Uranus, Saturn and Neptune — gradually shifted into their current orbits due to a series of interactions with one another's gravity.

With this in mind, researchers ran some simulations to explore how all that jostling for position might have affected the moons of Jupiter and Uranus in particular — and the results suggest that these two planets' moons only survived that tumultuous time because of a giant planet that didn't.

Potential histories of the solar system

Clement and his colleagues ran computer simulations of 122 possible versions of the early outer solar system, using different starting combinations of planets and different scenarios for the worlds' migration patterns. They ran each simulated version of the solar system's history several times, taking note of which versions were more likely to produce something that looks like the outer solar system as we know it today. In particular, the researchers were interested in the moons of gas giant Jupiter and ice giant Uranus.

"Planetary encounters, and the [changes in orbit] that result from them, are thought to have played a key role in sculpting many small body populations throughout the solar system," wrote Clement and his colleagues in their recent paper.

Other teams of astronomers have looked for clues about the movements of giant planets in the orbits of asteroids and other small objects, studying them like footprints to reconstruct how they might have been pushed or pulled into their current orbits by the gravity of giant planets on the move. The moons of Jupiter and Uranus offer an especially good set of clues, because it's likely that they've been more-or-less in their current orbits around their planets for most of our solar system's history. Jupiter's moons are in a chain of orbital resonances that could only have formed by the moons tugging gently on each other in passing over a long period of time, and crater records also suggest that Jupiter's moons are very, very old.

We live in an unlikely solar system

As it turns out, Jupiter and Uranus are lucky to have their entourages of moons at all.

Jupiter's moons only made it through the era of migrating giants in less than 15% of simulations; Uranus's moons survived only about 9% of the time.

In fact, scenarios that worked out well for one set of moons tended to be bad for the other: Jupiter's moons had better chances in simulations that started with two extra ice giants, while Uranus's moons survived more often when there was a single, but larger, ice giant. The probability that both giants' moons survive the same scenario is only about 1%.

Clement and his colleagues found only two scenarios in which both planets' moons survived, and both of those included one extra ice giant in the beginning.

"The solar system is the result of fairly unlikely instability evolution," wrote Clement and his colleagues. In other words, picture Dr. Strange grimly holding up two fingers during that battlefield scene in Avengers: Infinity War.

Our solar system’s secret, long-lost ice giant

In the most likely scenario, the solar system starts with five giant planets: the big four we know and love today, plus an extra ice giant — sort of the Pete Best of planets. Sometime in the solar system's first billion years or so, Jupiter's migration brings it within about 4.3 million miles (7 million kilometers) of the unlucky ice giant, giving the latter enough of a gravitational shove to achieve escape velocity. That long-lost ice giant is probably still drifting somewhere out there in interstellar space, cold and alone.

The ice giant getting booted out of the solar system isn't the thing that spared Jupiter's and Uranus' moons from a similar fate. But the fact that the ice giant was ever there in the first place altered the course of the other four planets' migrations just enough to spare Uranus more than one moderately close brush with another giant world's gravity — and kept that period of migration shorter than it otherwise would have been.

Jupiter's close encounter with the long-lost ice giant would've been enough to scramble its moons' orbits a bit, disrupting that neat chain of orbital resonances, but not enough to cause them to crash into each other or fling them out into interplanetary space (and Clement and his colleagues argue that they should have had time to gradually fidget themselves back into their resonances). Meanwhile, Uranus and its moons probably suffered at least two major shakeups: one when something large slammed into the planet and knocked it onto its side, and again during the giant planets' migration. But although both incidents probably caused a few dramatic collisions between the moons, they weren't strong enough to completely wreck the systems.

We may never know the details

During their simulations, Clement and his colleagues tested several things, varying the number and mass of giant planets in the solar system, their starting orbits, and the total mass of objects out in the Kuiper belt — but "the most relevant varied parameter is the initial ice giant number," they wrote.

Clement and his colleagues however note that simulations of the so-called "Nice model" they worked with are stochastic, meaning there's an element of randomness involved in what happens once objects in motion start interacting. And that means it's pretty likely that none of their simulations re-creates exactly what happened — just the general idea.

"It is highly likely that none of the modeled instabilities in the literature contain the precise sequence of encounters necessary to exactly reproduce all aspects of the solar system," the researchers wrote. But the simulation is a strong hint about the broad strokes, like the presence of a whole other planet, now lost in the void.

Johns Hopkins University planetary scientist Matthew Clement and his colleagues published their work in the journal Icarus.

Could Uranus and Neptune be full of rocks? One new study thinks so.

Uranus and Neptune are two planets that have historically been classified and thought of as "ice giants," orbiting far out in the freezing edges of our solar system. But it's possible that our understanding of these planets' makeup could be totally off, and their atmospheres could be full of rocks, researchers suggest in a new study.

"We found out that both Uranus and Neptune have their outer shells made mostly of rocks (and hydrogen and helium gas)," study author Yamila Miguel of the Netherlands Institute for Space Research told Space.com. This "goes against the common belief that they are ice-giant planets."

These two planets both have inner rocky cores surrounded by icy mantles enveloped by a thick atmosphere that has been thought to contain hydrogen, helium and methane gases as well as silicate clouds. In some high pressure areas, the gaseous atmosphere becomes fluid — but the results of this study suggest these atmospheres could also be littered with rocks.

This research team was inspired to take a closer look at Neptune and Uranus thanks to recent research which has suggested that objects in the trans-Neptunian region, an icy region beyond Neptune, are more rocky than icy. Previous studies have suggested objects like Pluto, comets, and Kuiper belt bodies indeed have rocky atmospheres, the new study's researchers explained. "We thought, if those objects are made mostly of rocks, maybe Uranus and Neptune [are] as well?" Miguel said.

To get to their conclusions, the researchers modeled the composition of both Uranus and Neptune, simulating the planets' envelopes (combined inner and outer atmosphere), mantles and cores. Based on conditions like temperature throughout each planet's atmospheric envelopes, the team found the conditions would cause silicate clouds in certain areas of these atmospheres to condense into rocky material.

So, while Uranus and Neptune are known as ice giants, orbiting far from our sun in the outer reaches of the solar system, they're rockier than you might expect an "ice" planet to be, at least according to this study.

While "they might have quite some ice in their interiors," Miguel said, "they are definitely not completely icy as we used to believe."

Miguel asserts that these new findings could even warrant a conversation about re-classifying these planets. "We should indeed change their classification so as not to be misleading," they suggest. "Rather than 'icy' or 'rocky,' we should simply call them minor giants or something like that."

To be clear, this new study isn't a definitive new classification of these planetary giants. However, it does raise interesting questions about their makeup: Could their atmospheres really be full of rocks? Are there other major aspects of their composition that we haven't yet uncovered? What other mysteries lie in the cold, far corners of our cosmic neighborhood?

This work was described in a study published May 5 in the journal Astronomy & Astrophysics.

New observations of Uranus's enigmatic outer rings have shown them to be even more mysterious than astronomers had thought, and their unusual properties hint at some puzzling things going on with the planet's system of moons.

These observations suggest that small, mysterious moons with surprisingly different natures are the source of the particles that make up the two outermost rings, and that there are probably even more undiscovered moons to add to the 29 already known around Uranus.

Uranus's rings are not like the bright, intricate structure of Saturn's famous rings. Quite the contrary: Uranus' rings were only discovered in 1977 when they were noticed to block the light of background stars during stellar occultations, when Uranus was seen to move in front of a star from our point of view on Earth.

Voyager 2 captured the first images of Uranus's rings when it flew past the seventh planet from the sun in January 1986, and since then the Hubble Space Telescope and the ten-meter telescopes at W. M. Keck Observatory on Mauna Kea in Hawaii have discovered further faint rings around the ice giant, bringing the total to 13. The rings are named after the Greek alphabet and the last two, outermost, rings named (𝛍) and nu (𝛎) were not discovered until a period of observations between 2003 and 2005 by a team led by the SETI Institute's Mark Showalter.

The mu- and nu-rings are especially puzzling. Those initial observations showed that the mu-ring was bluer than the nu-ring, which has a red tint. The colors are informative of their composition. Blue implies very small particles, while red is indicative of dust. It would seem that the mu- and nu-rings have very different origins, but no one knew what those origins were.

Now, by adding infrared data from the James Webb Space Telescope to the older Hubble and Keck observations, a team led by Imke de Pater of the University of California, Berkeley and including Showalter, has been able to produce the first complete reflectance spectrum of the rings, which refers to how they reflect sunlight. The spectrum confirmed their colors and provided some indication of their origin.

"By decoding the light from these rings, we can trace both their particle size distribution and composition, which sheds light on their origins, offering new insight into how the Uranian system and planets like it formed and evolved," said de Pater in a statement.

Uranus's moons are named after characters from the plays of William Shakespeare and a poem by Alexander Pope, a convention begun by John Herschel. The five large moons — Miranda, Oberon, Titania, Umbriel and Ariel — orbit Uranus farther out, but 14 of the small moons orbit Uranus closer than those five moons, and it is among these 14 moons that the mu- and nu-rings are found.

The reflectance spectrum shows that the mu-ring is made from particles of water-ice. This matches the only other blue ring in the solar system, namely Saturn's E-ring that is produced by cryovolcanism on Saturn's moon Enceladus, which squirts geysers of water into space. The icy particles in the mu-ring have even been traced back to their source: an irregular, 12-kilometer (7.5-mile) wide moon called Mab that was discovered by Showalter in 2003. Yet most of the other inner moons tend to be dustier and rockier. Why is Mab largely ice?

Meanwhile, the nu-ring is dirtier, with 10 to 15% of its composition made from carbon-rich organic compounds of the type typically found in the cold environs of the outer solar system. It would seem that the nu-ring is being produced by dust sputtered off undiscovered moonlets that reside within the group of inner moons.

"The nu-ring material is sourced from micrometeorite impacts on and collisions between unseen rocky bodies rich in organic materials, which must orbit between some of the known moons," said de Pater. "One interesting question is why the parent bodies sourcing these rings are so different in composition."

There are hints that the mu-ring is changing in brightness subtly, though what this clue is telling us is not yet understood. However, given the small size and faintness of these tiny moons, it would seem that solving the mysteries of Uranus and its system of rings and moons must await a new mission.

"I suspect we will need close-up images from a future spacecraft mission to Uranus in order to answer that question," said Showalter.

Fortunately a mission is in the works — funding permitting — since returning to Uranus was the top planetary priority in the most recent Decadal Survey from the National Academy of Sciences.

The findings were published on April 16 in the Journal of Geophysical Research: Planets.

March's new moon phase is upon us, bringing gorgeous dark skies free of natural light pollution — perfect for exploring constellations and deep sky objects that are all too often obscured by moonlight!

This month's new moon occurs at 9:23 p.m. EDT on March 18 (0223 GMT on March 19) as the lunar disk passes between the sun and Earth. Around this time, the lunar disk is invisible from our perspective, lost in the sun's glare.

It's an ideal time to escape city lights and hunt for stars, galaxies and elusive natural phenomena in the spring skies. Here's what to look for before the waxing crescent moon returns ahead of its first quarter phase on March 25.

Visible planets

Stake out a spot with a clear view to the west for a chance to see Venus shining low on the horizon in the hour following sunset. This inner world — often referred to as Earth's twin due to its size and rocky composition — will disappear swiftly below the horizon roughly 90 minutes after the setting sun, so be quick!

With the moon tucked safely below the horizon, Jupiter will be the brightest object in the night sky. It can be found shining high overhead in the southern sky as the sun sets in mid-March, close to the bright stars Castor and Pollux in the constellation Gemini.

Uranus, meanwhile, lurks in the constellation Taurus, too dim for the unaided eye to see. To find Uranus, first locate the bright red star Aldebaran, which shines to the right of Orion in the evening sky. Uranus tiny aqua disk can be found by sweeping an 8-inch (200 mm) scope across the patch of sky 5 degrees to the lower right of Aldebaran — roughly the width of your three middle fingers held at arm's length — close to the hazy light of the Pleiades open star cluster.

Mercury is visible as a predawn planet in mid-to-late March, which will appear rising low on the eastern horizon before swiftly becoming lost in the glare of the rising sun. Mars, and Neptune remain too close to the sun to be seen.

As always, the greatest care must be taken to never point a telescope or binoculars close to the rising sun, as doing so will permanently and immediately damage your vision.

Stars and constellations

Look above the southwestern horizon in the hours following sunset to trace the bright stars of the Winter Hexagon shining defiantly in the early spring sky.

Start with Sirius — the brightest star in the night sky — which can be found above the southern evening horizon in the constellation Canis Major, the Big Dog.

Next, find the brilliant light of the blue supergiant star Rigel twinkling beneath the familiar sight of Orion's Belt to the upper right of Sirius, before leaping higher in the west to the red star Aldebaran, which forms the right eye of the celestial bull in the constellation Taurus.

Our next stop is Capella, higher still, which stands as the brightest point in the constellation Auriga, before we travel to the east to find bright Pollux to the upper left of Jupiter, which represents the head of one of two immortal twins in the constellation Gemini. The final Winter Hexagon star, Procyon, can be found shining between Pollux and Sirius, in the constellation Canis Minor, the "Little Dog".

Star clusters and deep-sky objects

The nights surrounding the new moon phase are a great time to spot the ancient diffuse light of star clusters glowing in the pristinely dark spring sky.

Allow at least 20 minutes for your eyes to adapt to the dark before turning your gaze back to the constellation Taurus and red Aldebaran. The "V" formation of stars extended from it is the Hyades open star cluster, which represents the face of a great bull charging towards Orion, the hunter.

From there, look about 15 degrees to the right of the Hyades to see the ancient light of the Pleiades star cluster, appearing as a hazy patch of light to the unaided eye from a dark sky location. A pair of 10X50 binoculars will allow you to see its seven brightest members — from which it gained the nickname of the "Seven Sisters" — while a small telescope will bring dozens more of its 1,000-strong stars into view.

To the left of Castor and Pollux lies the constellation Cancer, the crab, the core of which plays host to the 100-strong stellar population of the Beehive Cluster (M44), which is visible as a small, misty patch of light on moonless nights.

The new moon is also an ideal time to observe the light of ancient galaxies, as spring brings a string of constellations packed with wonderful galactic targets to prominence. Check out our guide to the spring galaxy season to find out more!

Zodiacal light

If you're lucky, you may spot a strange pillar of pale light extending up from the western horizon in the hours following sunset in late March. This phenomenon, known as zodiacal light, occurs when sunlight reflects off a vast cloud of dust spread along the plane of the solar system, known as the ecliptic.

Want to get a closer look at the wonders of the post-sunset realm? Then be sure to read our roundup of the top telescopes and binoculars for observing the night sky. If photography is your thing, then you'd do well to read our picks of the best lenses and camera bodies for astrophotography in 2026.

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.

NASA's Chandra X-ray Observatory has transformed new telescope views of Jupiter, Saturn and Uranus from this month's "planetary parade" into striking soundscapes — capturing everything from Jupiter's crackling auroras to the sweeping arc of Saturn's rings.

The newly released sonifications translate X-ray and multiwavelength observations of the three outer worlds into immersive audio experiences, turning streams of data from the space telescope into layered musical compositions. Timed to coincide with the rare alignment of several bright planets in the night sky, the project continues Chandra's broader effort to observe the universe through more than just sight, according to a statement from NASA sharing the new sonifications.

Sonification is the process of converting data into sound by mapping brightness, position and energy to pitch, volume and instrument choice. The process begins with real data collected by Chandra, which detects high-energy radiation produced when solar X-rays are reflected by planets, moons and other bodies in the solar system. Those observations are then combined with imagery from other observatories, including the Hubble Space Telescope and past planetary missions, to build a fuller, multiwavelength portrait.

A digital "activation line" then sweeps across the image. As it encounters bright auroras, planetary disks or rings, the data values are translated into sound. Brighter X-ray emissions may become higher or louder notes, while vertical position can shift pitch and stereo placement.

"Sonifications expand options for people to explore what telescopes discover in space, an example of NASA's ongoing commitment to share its data as widely as possible," officials said in the statement.

In Jupiter's sonification, shimmering, wind-like tones evoke the giant planet's powerful X-ray auroras, while deeper notes roll underneath like distant thunder, reflecting the turbulence of its striped atmosphere and cloud layers. Saturn's rings sweep in rising and falling siren-like tones, while deep bass notes represent the planet itself. Uranus unfolds more subtly, with gentler, cello sounds that trace the icy planet's arcing ring, mirroring its cooler, more subdued presence at the edge of the planetary lineup.

Previous sonifications have drawn on observations of the Milky Way, distant galaxies, stars, supernovae, nebulae and black holes. One example, based on the famous black hole in Messier 87, translates its powerful jets into sweeping changes in pitch and intensity, followed by lower, sustained tones representing vast clouds of hot gas, with brief, bell-like notes marking individual stars.

Just as astronomers assign visible colors to otherwise invisible wavelengths to make images comprehensible, sonification gives numerical data distinct sonic qualities. Mapping the planets' crackle, sweep and hum into different tones brings the solar system to life through both sight and sound.

Jupiter, Saturn, Venus, Neptune, Uranus and Mercury are staring in a "planetary parade" this week, but your ability to actually spot them will depend on preparation, equipment and, as always, a spot of luck with the weather.

Most of this week's naked-eye planetary action will take place low in the western sky, which is where the aforementioned preparation comes in. Be sure to stake out a raised location with a clear view of the horizon well ahead of time — you can use a smartphone stargazing app to figure out exactly where the planets will be in your local environment, so there's no need to guess.

Do so, and you'll be granted a rare, if challenging opportunity to spot Mercury shining 10 degrees — roughly the width of your clenched fist held at arm's length — above the late winter skyline, with Venus close to its left, floundering in the glow of the setting sun. Saturn, meanwhile, will glow less than 10 degrees to the upper left of Venus, with a distant cousin lurking nearby, but more on that later.

Mercury and Venus will follow the sun out of sight roughly an hour after sunset, briefly becoming more visible as the sky darkens and they grow closer to the horizon. Jupiter, meanwhile, will shine high in the eastern sky, with the waxing gibbous moon below, obscuring the stars of the constellation Cancer with its reflected light.

The next two planets will need a little added magnification to spot — and even then, you'll have the odds stacked against you.

The ice giant Neptune will be positioned two degrees to the right of Saturn, but will be too dim to spot with the unaided eye. Under dark skies, a telescope with an aperture of 8 inches (200 millimeters) or more can reveal its tiny bluish disk. However its position low on the horizon and close to the glare of our parent star will make it a challenge to spot on the nights surrounding Feb. 28. As always the utmost care must be taken to ensure that the sun is firmly below the horizon before pointing telescopic equipment in its general direction.

Uranus, meanwhile, can be found by sweeping your scope across the patch of sky 5 degrees below the Pleiades open star cluster, to the right of the "V" formation of stars in the constellation Taurus in the hours following sunset. Again, those new to the night sky may want to use a smartphone astronomy app, which makes use of augmented reality technology to help you pinpoint everything from constellations and planets to galaxies and meteor shower radiants.

Award-winning night sky photographer Josh Dury grappled with the sheer scope of the scene along with the glow of the setting sun and other challenges to capture a gorgeous long exposure view of the planetary parade earlier this week as it brightened the sky over the south of England.

For more, check out our handy guide on the equipment needed to see and photograph the planets. If you're into photography, then why not also read our roundups of the best cameras and lenses for capturing the night sky?

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

Look to the western horizon at sunset on Feb. 20 to witness an incredible sight, as three planets shine below the slender crescent of the waxing moon, with Jupiter glowing high overhead in the winter sky.

The upturned sickle-shape of the 18%-lit moon will appear 40 degrees above the horizon as the sun sets, with a string of bright "evening stars" representing Venus, Mercury and Saturn arrayed beneath, fighting for attention in the glow of the setting sun.

Saturn will be positioned 15 degrees directly below the crescent moon, with Mercury less than 10 degrees— roughly the width of your clenched fist held at arm's length — to its lower right. Mercury is currently in prime viewing position, having just passed its point of greatest eastern elongation on Feb. 19, when it was at its furthest from the sun in Earth's sky in its current evening apparition.

Find a spot with a clear view to the west for a chance to see Venus shining directly below Mercury, less than 10 degrees above the horizon at sunset. Neptune will also be present less than 1 degree — approximately the width of your little finger — to the right of Saturn, though it'll be too dim to spot with the naked eye.

Neptune is so distant that the blue spec of its disk can only be seen with the aid of an 8-inch telescope, but utmost care must be taken to ensure that the sun is well below the horizon before pointing any telescopic equipment in its direction.

Uranus, meanwhile, will be five degrees below the Pleiades on Feb. 20 and while technically just bright enough to spot with the naked eye from a dark sky location, the planet will also benefit from the magnifying power of a telescope to spot its tiny aqua disk.

Jupiter dominates the sky this time of year and can be found high in the east at sunset, glowing with the bright stars Castor and Pollux in the constellation Gemini. A 6-inch telescope will reveal details in the cloud bands lining its surface, along with its four largest moons, Io, Ganymede, Europa and Callisto.

The lunar crescent will also make for a fascinating telescopic target, just three days out from its new moon phase on Feb. 17. Look out for the dark forms of Mare Crisium and Mare Fecunditatis darkening the sunlit wedge of Earth's satellite, which formed when ancient lava flows flooded networks of impact craters before hardening many millions of years ago.

Next, sweep your telescope across the line separating night from day on the lunar surface — known as the terminator — to spot a myriad of shadowed impact craters scarring the lunar surface.

Want to explore the planets of the solar system for yourself? Then be sure to read our roundup of the best telescopes available in 2026. If you're into photography you'll want to peruse our picks of the best cameras and lenses for capturing the night sky.

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

An international team of researchers has uncovered new insights into the upper atmosphere of Uranus, where ions swirling above the ice giant planet's clouds meet the magnetic field surrounding the world.

"Uranus's magnetosphere is one of the strangest in the solar system," Paola Tiranti, a researcher at Northumbria University in the U.K., said in a statement. "It's tilted and offset from the planet's rotation axis, which means its auroras sweep across the surface in complex ways."

Using the Near-Infrared Spectrograph (NIRSpec) instrument aboard the James Webb Space Telescope (JWST), the team studied Uranus as it rotated. The researchers observed how temperature and charged particles "vary with height across the planet," according to the statement; the resulting data could help scientists understand more about how energy behaves in ice giants' upper layers.

"By revealing Uranus's vertical structure in such detail, Webb is helping us understand the energy balance of the ice giants," Tiranti said. "This is a crucial step towards characterizing giant planets beyond our solar system."

The JWST continues to provide unprecedented detail on comic phenomena located millions, even billions, of miles away from us. With such detailed data available, scientists are still able to make new discoveries about the planets in our solar system. The telescope has previously had its sights set on Uranus too, even discovering a new moon of the planet in 2025.

"This is the first time we've been able to see Uranus's upper atmosphere in three dimensions," said Paola. "With Webb's sensitivity, we can trace how energy moves upward through the planet's atmosphere and even see the influence of its lopsided magnetic field."

Voyager 2 provided our first close-up data and images of Uranus way back in 1986. The flyby helped scientists figure out that Uranus is very cold compared to its neighboring planets — in fact, around then is when we found out Uranus is our solar system's coldest planet.

"Webb's data confirm that Uranus's upper atmosphere is still cooling, extending a trend that began in the early 1990s," said Paola. "The team measured an average temperature of around 426 kelvins (about 150 degrees Celsius), lower than values recorded by ground-based telescopes or previous spacecraft."

The research was published on Feb. 19 in the journal Geophysical Research Letters.

Want to know when each planet will be at its best or when you can catch eye-catching planetary pairings in 2026?

This guide breaks down the major planetary events of the year, from conjunctions to oppositions to close planet-star encounters.

Related: Night sky tonight live blog

Mercury

Mercury, the smallest of the planets visible to the naked eye, appears as an evening star in the western sky, setting about an hour after the sun. As a morning star, it rises about an hour before the sun in the eastern sky. To view the planet, a clear, unobstructed view of the horizon is essential. Mercury usually appears as a bright "star" with a yellowish or ochre tint.

Visibility windows in 2026

• Evenings: Feb. 5–26; June 1–22; Sept. 28–Oct. 19
• Mornings: March 27– April 17; July 26– Aug. 16; Nov. 13– Dec. 4

When will it be at its best?

• Evening: Feb. 5–26
• Morning: Nov. 13– Dec. 4

On the evening of Feb. 18, about 30 minutes after sunset, Mercury will sit just 1 degree above a slender waxing crescent moon low in the west-southwest.

Venus

Venus, with its nearly circular orbit and a diameter only 400 miles (640 kilometers) smaller than Earth's, shines with a brilliant, steady silvery light.

Visibility windows in 2026

• Evenings: March 8– Oct. 14
• Mornings: Nov. 3– Dec. 31

When will it be at its best?

Venus reaches greatest brilliancy in the evening sky on Sept. 19 and in the morning sky on Nov. 29. In late September through mid-October, and again through most of November, Venus will show a striking crescent phase in telescopes and steady binoculars.

Notable conjunctions:

• March 8: Venus passes 1 degree to the upper right of Saturn.
• June 9: Venus passes 1.6 degrees to the upper right of Jupiter — a brilliant sight in the west-northwest 45 minutes after sunset.
• Nov. 7 (morning): Shortly before sunrise, look low to the east-southeast for Venus, a crescent moon, and the star Spica, all fitting within 2.5 degrees.

Mars

Mars, long associated with Ares, the Greek god of war, shines like a star with a yellowish-orange hue and can vary considerably in brightness.

Visibility in 2026

• Mornings: March 18- Dec. 31

When will it be at its best?

This is an "off" year for Mars. The planet begins 2026 lost in the sun's glare and reaches solar conjunction on Jan. 9, sitting on the far side of the solar system about 223 million miles from Earth.

Mars begins to reappear in the third week of March, rising before sunrise among the faint stars of Aquarius. It moves into Taurus for the first half of summer, shining only around magnitude +1.3.

Sky highlights:

• Sept. 25: Castor and Pollux point directly toward Mars.
• Oct. 11: Mars passes through the Beehive Cluster in Cancer — an attractive sight in binoculars.
• Nov. 26: Mars passes 1.7 degrees above Regulus in Leo, creating a dramatic color contrast.
• By late December, Mars brightens to magnitude –0.1 and will rival Arcturus in both color and brightness.
• Feb. 19, 2027: Mars reaches its next opposition, so it steadily approaches Earth late in 2026.

Notable conjunctions:

• April 20: Mars aligns closely with Saturn and Mercury.
• July 4: Mars passes just 0.1 degree south of Uranus, offering a superb guidepost for locating Uranus.
• Nov. 16: Mars passes 1.2 degrees to the upper left of Jupiter.

Jupiter

Jupiter, the giant planet with a diameter about 11 times bigger than Earth's, shines with a bright silver-white luster.

Visibility windows in 2026

• Mornings: Jan. 1–9; Aug. 19– Dec. 31
• Evenings: Jan. 10–July 7

Jupiter reaches opposition on Jan. 10 and shines brightest from Jan. 1–22 at magnitude –2.7 in Gemini. It enters Cancer on June 22 and Leo on Sept. 24, where it remains through year's end.

On June 9, Jupiter pairs with Venus in a stunning "double planet" display low in the west-northwest at dusk.

Oct. 6 lunar occultation

On the morning of Oct. 6, observers across most of North America (excluding the far West) and northern Cuba will witness a spectacular lunar occultation of Jupiter. A waning crescent moon will slide directly in front of Jupiter, hiding it for up to an hour depending on location. Jupiter disappears behind the bright limb and reemerges dramatically from the moon's dark side.

Saturn

Saturn shines as a yellowish-white "star" of moderate brightness. Its famous rings, invisible to the naked eye, turned edge-on in 2025 and were nearly impossible to see for weeks. They are now slowly opening up again.

Constellation path in 2026:

• Starts in Aquarius (to Jan. 14)
• Enters Pisces (Jan. 14– April 8)
• Moves through Cetus (April 9– June 2)
• Back into Pisces (June 3–Sept 4)
• Back into Cetus (from Sept. 5 onward)

Visibility windows in 2026

• Evenings: Jan. 1–March 8; Oct. 4–Dec. 31
• Mornings: April 12– Oct. 3

Saturn reaches opposition on Oct. 4 and is brightest Sept. 24–Oct. 9.

Notable conjunctions:

• Feb. 15: Saturn sits less than 1 degree from Neptune, though Neptune is much fainter.
• Apr. 20: Saturn aligns with Mars and Mercury.

Uranus

Uranus can be glimpsed with the naked eye under very dark skies by keen-eyed observers. At magnitude +5.6, it is easily found with binoculars; small telescopes show a tiny greenish disk.

Uranus spends all of 2026 in Taurus.

Visibility windows in 2026

• Evenings: Jan. 1–May 5; Nov. 25– Dec. 31
• Mornings: June 9–Nov. 24

Uranus reaches opposition on Nov. 25 and is brightest Oct. 24–Dec. 30.

On July 4, Uranus sits only 0.1 degree north of Mars, making Mars an ideal pointer to the seventh planet. Mars will outshine Uranus by a factor of about 158.

Neptune

Neptune remains in Pisces throughout 2026. At magnitude +7.8, it is visible only in binoculars or a telescope and appears bluish-gray.

Visibility windows in 2026

• Evenings: Jan. 1–March 6; Sept. 25–Dec. 31
• Mornings: April. 8– Sept. 24

Neptune reaches opposition on Sept. 25 and is brightest July 28–Nov. 24.

On Feb. 15, Neptune lies less than 1 degree to the upper right of Saturn, though Neptune is only about 1/525 as bright.

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 and other publications.

The Voyager 2 mission may have caught Uranus at a special time during which the ice giant's radiation belts were being supercharged with electrons accelerated by a similar process to what can drive geomagnetic storms on Earth.

This realization, resulting from placing old data from Voyager 2 under new scrutiny, could help explain several puzzling aspects of Uranus's magnetic envelope.

When the fast component of the solar wind, which emanates through coronal holes on the sun and is somewhat irregular, slams into slower portions of the solar wind, it results in electromagnetic shocks in the sleet of charged particles carried on the wind. Such an event is referred to as a co-rotating interaction region, and when one occurs near Earth, it can be one of the causes of geomagnetic storms that can result in the aurora.

The solar wind extends out past Earth, and even beyond Uranus, Neptune and the Kuiper Belt to form the 'heliosphere', which is a magnetic bubble around the solar system. The realization that a co-rotating interaction region may have been passing Uranus at the same time as the Voyager 2 encounter on Jan. 24, 1986 could be the missing piece of the puzzle that has eluded scientists for nearly four decades.

Voyager 2 remains the only mission to have visited Uranus (and Neptune, for that matter). What it found was a cold, icy gas bag with a very strange magnetosphere, which is what we call the magnetic envelope generated by the planet's intrinsic magnetic field. The north–south orientation of that magnetic field is tilted by 59 degrees relative to Uranus' axis of rotation, which itself is tilted by 98 degrees relative to the ecliptic plane. Furthermore, the magnetosphere is off-center inside Uranus, allowing for a much stronger magnetic field in the north than in the south.

Just as Earth's magnetosphere is ringed by belts of radiation in the form of charged particles, so is Uranus. Yet, when Voyager 2 arrived in 1986, it found that there was barely any plasma (ionized gas) contained within Uranus' magnetosphere. In fact, the magnetosphere had been compressed and the plasma seemingly squeezed out. What was in abundance were electrons, contained in surprisingly densely populated belts.

Back in 1986, scientists thought that a solar-wind event like a co-rotating interaction region would scatter electrons present in Uranus' magnetosphere into the planet's atmosphere. However, almost four decades of studying the solar wind and how it interacts with planets has taught us something different.

"Science has come a long way since the Voyager 2 fly-by," said the Southwest Research Institute's Robert Allen, who led the new research, in a statement. "We decided to take a comparative approach looking at the Voyager 2 data and compare it to Earth observations we've made in the decades since."

While on some occasions co-rotating interaction regions can scatter electrons into a planet's atmosphere, studies of their interaction with Earth have shown that such an event can also dump a lot of energy into the magnetosphere.

"In 2019, Earth experienced one of these events, which caused an immense amount of radiation-belt electron acceleration," said Sarah Vines, who is also from the Southwest Research Institute. "If a similar mechanism interacted with the Uranian system, it would explain why Voyager 2 saw all this unexpected additional energy."

In the absence of a second mission to Uranus after Voyager 2, scientists have learned to squeeze all they can out of the old Voyager 2 data instead, using new insights and techniques garnered over the past four decades, to learn more about the ice giant. These new findings come just a year after another team looked at the old data to conclude that the solar wind had indeed compressed Uranus' magnetosphere, squeezing out the plasma normally present.

For those four decades, scientists had thought that Uranus' magnetosphere was always in this bizarre state, but now we are learning that we simply caught it at a rare moment, and that what Voyager 2 measured might not be the status quo.

"This is just one more reason to send a mission targeting Uranus," said Allen.

Uranus is not alone in having a strange magnetosphere. When Voyager 2 encountered Neptune three-and-a-half years later, it found that it too had a displaced and tilted magnetosphere, just like Uranus. Indeed, the findings of the new analysis of the old Uranus data "have some important implications for similar systems, such as Neptune's," added Allen.

Perhaps misaligned magnetospheres are typical of all ice giants, both in the solar system or beyond. Or perhaps they are atypical, or symptoms of Uranus and Neptune's unique histories. Either way, new missions are urgently needed to provide the first close-up data in nearly 40 years and counting. Fortunately, a new Uranus mission is currently a top priority for NASA.

The new analysis of the old Voyager 2 data can be found in a paper published on Nov. 21 in Geophysical Research Letters.

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

The solar system's oddball planet has some pretty odd moons, too. The first infrared spectra of Uranus's small inner moons, which will be presented on 18 December at the 2025 AGU Annual Meeting in New Orleans, have shown that their surfaces are much redder, much darker, and more water-poor than the larger moons orbiting far from the planet.

"We were trying to see how these properties varied across the rings and moons," said Matt Hedman, a planetary scientist at the University of Idaho in Moscow and a coauthor on the research. "We didn't have a lot of information about their spectra before because they’re hard to observe."

The new observations also revealed that some moons were not quite where they should have been, highlighting how much more astronomers have to learn about the dynamics of the Uranian system.

Small, dark, and red

In 1986, Voyager 2 flew past Uranus in humanity's only visit to the system. At that time, astronomers knew only of the planet's five major moons and a handful of rings. Voyager 2 discovered 11 more moons and was able to roughly measure their sizes. Since then, scientists have used ground- and space-based telescopes to discover more than a dozen additional satellites, bringing Uranus's moon total to 29.

Many of the more recently discovered moons are pretty tiny, from Sycorax at 150 kilometers across to Mab and Cupid at just 10 kilometers. Most of them also orbit within or just outside Uranus's ring system, close to the much brighter planet.

All of these properties have made it tricky for astronomers to learn more about the smallest Uranian moons. That’s where the infrared powerhouse James Webb Space Telescope (JWST) comes in.

"Part of what makes JWST particularly good for this compared to, say, Hubble and other optical telescopes, is that in the infrared, Uranus is much fainter, so you can see the things orbiting it way more easily," Hedman explained. What's more, all of the spectral features the team was interested in, like water ice, occur at wavelengths that JWST can observe.

The researchers observed Uranus at several infrared wavelengths in February and got a deep look at the inner portions of the planetary system. They wanted to characterize the known small moons and search for new ones. They did discover a previously unknown moon, temporarily named S/2025 U1, orbiting just outside the epsilon ring.

Those observations also provided the first information on the infrared brightnesses of the smallest moons, many of which have remained elusive since the Voyager flyby.

"Most of the rings and inner moons show very similar properties," Hedman said. They tend to be much redder, darker, and more water-poor when compared with the larger outer moons Miranda, Ariel, Umbriel, Titania, and Oberon.

"And then there's Mab," Hedman added.

The new spectra show that Mab's surface is bluer and more water-rich than the other inner moons, said Jacob Herman, a physics graduate student at the University of Idaho and lead author on the research. In fact, its surface spectrum looks very similar to Miranda's, the major moon that orbits closest to the rings and to Mab. Miranda's jigsaw surface suggests a messy history.

Did the two moons encounter each other sometime during Uranus's chaotic past? Could that encounter be related to Uranus’s mu ring, which is likely generated by material sloughing off Mab? Hedman hopes that future observations or a long-term mission to Uranus will provide those answers.

"These new measurements significantly expand our current knowledge, revealing, for instance, striking variations in the composition and reflectivity of the surfaces of moons such as Mab, Cupid, and Perdita," said Jadilene Xavier, an astrophysicist at São Paulo State University in Guaratinguetá, Brazil, who was not involved with this research.

"There is still much to be discovered about Uranus's small inner moons, particularly regarding their origin, composition, and long-term orbital stability," Xavier said. "More precise data on their density, three-dimensional shape, and surface properties would be essential to determine whether these moons are fragments produced by collisions, captured objects, or primordial remnants associated with the formation of Uranus's ring system."

Just a Little Bit Off

Because Voyager 2 spent only a short time visiting Uranus, it could provide only limited information about the small moons' orbital periods and distances, sometimes with large uncertainties. When the researchers compared the moons' current positions with the positions predicted by Voyager 2 data, some of the moons were not where they seemingly should have been.

"Perdita was quite a bit off," Herman said. "And there's also Cupid, which was surprising." The positions of Cordelia, Ophelia, Cressida, and Desdemona were also off, but not by much. The team is still trying to figure out whether the differences are just a matter of having more precise observations of these tiny objects or if there are unknown dynamics in play.

"These new observations are quite useful for improving our understanding of the inner Uranian system, especially its orbital dynamics," said Matija Ćuk, who researches solar system dynamics at the SETI Institute in Mountain View, Calif.

Ćuk, who was not involved with this research, pointed out that Cordelia and Ophelia shepherd Uranus's epsilon ring, Cressida and Desdemona are part of a pack of moons with chaotic orbits, and Perdita is known to interact with another moon, Belinda. "So the fact that these [five] moons are not in their predicted positions is valuable for understanding the system, but I wouldn't say it's unexpected," Ćuk said.

These observations hint at just how many mysteries Uranus is still hiding.

"For a dynamicist like me," Ćuk said, "knowing the precise masses of these moons would be ideal, because then we could predict their future interactions and also estimate with some confidence how stable they are on long timescales."

Hedman and their team plan to observe the Uranian system again with JWST, are looking through archived and technical images, and hope to establish long-term monitoring to better understand the moons' dynamics and possibly estimate their masses. The researchers are also leaning on their colleagues who simulate planetary orbits to better understand how Uranus's moons and rings might be influencing each other.

"It's a very dynamic and interconnected system," Herman said.

Small icy moons in the outer reaches of our solar system may hide boiling oceans underneath their surfaces, a new study finds.

Previous research found that some of the icy moons in the outer solar system, such as Saturn's moon Enceladus, are not frozen solid. Instead, they may host oceans between their ice shells and rocky cores. Because on Earth, there is virtually life wherever there is water, this has raised the hope that such hidden oceans may be the best sites in our solar system to look for extraterrestrial life.

To shed light on the buried oceans within these icy moons, geophysicist Maxwell Rudolph at the University of California, Davis, previously examined the forces that might result from changes in the thickness of the icy shells of these moons over the course of hundreds of millions of years.

"We were especially interested in whether the stresses could lead to the formation of cracks that connect the surface to the subsurface ocean, allowing the eruption of liquid water from a potentially habitable ocean to space," Rudolph told Space.com.

In prior work, Rudolph and his colleagues focused on what happens to these moons when their ice shells get thicker. As ice takes up a greater volume than a similar mass of liquid water, freezing places pressure on ice shells, generating features such as the "tiger stripes" seen on Enceladus.

In the new study, the researchers explored what happens when the icy shells of these moons become thinner due to melting from the bottom. For instance, previous research discovered a wobble in the orbit of Saturn's moon Mimas was potentially due to an ocean under its icy crust that likely arose in the past 10 million years, given how its surface still retains many ancient features, such as craters. This ocean likely resulted when Mimas's shell melted due to interactions with other Saturnian moons.

The scientists discovered that if these icy shells thin, the pressure they place on the oceans drops. On the smallest icy moons, such as Mimas and Enceladus or Uranus's Miranda, the pressure could lower enough to reach a so-called "triple point" — a specific combination of temperature and pressure in which ice, liquid water and water vapor can all co-exist. This can lead the layers of the oceans closest to their icy shells to boil after the icy shells thin by about three to nine miles (five to 15 kilometers).

"This is the kind of boiling that happens at low temperatures, not the kind of boiling that occurs in kitchens when you heat water up to past 100 degrees C [212 degrees F]," Rudolph said. "It's instead boiling very close to zero degrees C [32 degrees F]. So for any potential life forms below that boiling area, life could go on as usual."

In contrast, on larger ice moons more than 370 miles (600 km) wide, such as Uranus's Titania, the drop in pressure from melting ice would instead cause the ice shell to crack before the triple point for water is reached, the team calculated. The researchers suggest that features of Titania's geology, such as wrinkle ridges, might have resulted from a period of ice shell thinning followed by re-thickening.

The gases from boiling might have a number of effects, such as the formation of clathrates — complex icy structures that entrap gas molecules. "Future work will address these processes in detail to understand what happens to gas once it has been released from an ocean and what kinds of surface features we would expect to form in association with these processes," Rudolph said.

The scientists detailed their findings online Nov. 24 in the journal Nature Astronomy.

November is the best month of 2025 to catch a glimpse of the distant ice giant Uranus as it shines at opposition, though you'll still need a telescope if you hope to spot the elusive planet hiding among the stars of the constellation Taurus.

Uranus will reach opposition at 7:17 a.m. EST (1217 GMT) on Nov. 21, when it will be positioned opposite the sun in Earth's sky. according to the astronomy website In-the-sky.org. The weeks surrounding opposition present a perfect opportunity to hunt for the distant ice giant as it stays visible from dusk to dawn in the Autumn night sky.

The ice giant shines with an apparent brightness — or magnitude — of +5.6 around the time of opposition, which means that it's technically possible to spot it with the naked eye under perfect dark sky conditions. (On the magnitude scale used by astronomers, lower numbers signify brighter objects). For example, at its brightest, the planet Venus shines with a magnitude of about -4.6.) However, a pair of binoculars or ideally a backyard telescope with an aperture of 8 inches (200mm) or more will make spotting the ancient world a whole lot easier.

How to find Uranus

Look to the east in the hours following sunset on Nov. 21 to find the stars of the constellation Taurus shining low on the horizon, with the combined light of the Pleiades open star cluster glowing roughly 10 degrees, or the width of your clenched fist held at arm's length, above it.

Uranus can be found in a patch of sky less than 5 degrees to the lower right of the Pleiades, appearing as a tiny aqua dot against the blackness of space. Whilst this may seem underwhelming at first glance, it's important to remember exactly what you're looking at — a world 1.72 billion miles (2.77 billion km) from Earth, four times the size of our blue marble, which has only been visited by a single spacecraft in the history of our species.

Hoping to catch a glimpse of Uranus in November? Then check out our roundups of the best telescopes, binoculars and smart telescopes available for purchase in 2025. If astrophotography is your passion then be sure to read our guides to the best cameras and lenses for capturing the night sky to ensure that you're ready to immortalize the next big stargazing event!

Look to the western sky in the hours preceding dawn on Nov. 6 to see the moon shine close to the constellation Taurus and the stars of the Pleiades open cluster.

The 94%-lit moon will appear roughly halfway up the western sky in the hours before sunrise on Nov. 6, with the stars of the Pleiades appearing as a hazy patch of light 5 degrees to its upper left — though they'll be a challenge to spot in the glow of the bright near-full moon. Remember, the width of your three middle fingers held at arm's length spans roughly 5 degrees in the night sky.

A pair of 10x50 binoculars will help reveal the seven brightest stars of the Pleiades open cluster — Merope, Electra, Maia, Taygete, Asterope, Alcyone and Celaeno, the "Seven Sisters" — along with a phalanx of dimmer stars belonging to the 1,000strong stellar hive.

Look 5 degrees to the lower left of the Pleiades to find the patch of sky containing Uranus. The distant ice giant has a magnitude — or brightness — of just +5.6, rendering it incredibly difficult to spot with the naked eye even under perfect dark sky conditions.

However, a telescope with an aperture of 8-inches or more will reveal Uranus as a tiny blue dot in the eyepiece under good atmospheric conditions. That may sound unimpressive until you remember what you're looking at — a titanic world four times the size of Earth, which is separated from us by a gulf of 1.72 billion miles (2.78 billion kilometers)!

Stargazers hoping to get a closer look at the planets of the solar system should read our roundup of the best telescope deals available in 2025, along with our nightly skywatching guide that lists all of the top stargazing sights on display in November.

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

Saturn isn't the only planet in our solar system with a ring system. While Saturn's rings are the most dramatic, the three other gas giants — Jupiter, Neptune, and Uranus — each have a ring system as well. But the fun doesn't stop there. Astronomers have also spotted rings around smaller celestial bodies: dwarf planets Haumea and Quaoar, as well as centaur Chariklo.

Now, 2060 Chiron, better known as just Chiron, is the latest celestial body to join the party. In analyzing observations of Chiron taken by Brazil's Pico dos Dias Observatory in 2023, astronomers have just spotted four rings plus diffuse material around this icy centaur, which was first sighted in 1977.

Centaurs are a class of celestial objects that are a cross between comets and asteroids, located between Jupiter and Neptune. Chiron, which orbits the sun between Saturn and Uranus, is composed of rock, water ice, and organic compounds, and it's approximately 125 miles (200 kilometers) in diameter.

Its rings — thought to be made of water ice and rocky material, potentially from a collision between Chiron and another celestial body — circle the centaur at approximately 170 miles (273 km), 202 miles (325 km), 272 miles (438 km) and 870 miles (1,400 km) from its center. The distant fourth ring, researchers note, might not ultimately be stable enough to be considered a ring, so further observations are necessary.

What's special about Chiron's rings is that they're still forming; this marks the first time astronomers have ever seen a ring system under formation. By comparing the 2023 observations to previous ones from 2022, 2018, and 2011, researchers determined that the ring system has been evolving rapidly.

"It is an evolving system that will help us understand the dynamical mechanisms governing the creation of rings and satellites around small bodies, with potential implications for various types of disk dynamics in the universe," astronomer Braga Ribas of the Federal University of Technology-Parana and the Interinstitutional Laboratory of e-Astronomy in Brazil, who co-authored a study on the research, told Reuters.

The team's research was published in the Astrophysical Journal Letters on October 14, 2025.

Astronomers have long called Uranus and Neptune the "ice giants" because models suggested that these outer planets' interiors are largely made of mixtures of water, ammonia and other ices — compounds that freeze easily in deep space. But new research reveals that we actually know very little about what's going on inside these planets, causing researchers to propose that Uranus and Neptune be called "rocky giants" instead.

The problem with Uranus and Neptune is that we have extremely little data available to us. Unlike Jupiter and Saturn, both of which have received dedicated missions like the Cassini probe and the Juno spacecraft, the outer planets have not received any visitors since the Voyager 2 flybys more than 30 years ago.

So, to build an understanding of these planets' interiors, we must rely on a variety of indirect clues, like their magnetic fields, observations of surface atmosphere features, and subtle changes in the orbits of their moons. For decades, models of solar system formation dictated that the outer realms of the solar system were dominated by molecules like water and ammonia ice. So naturally, those compounds would make up the bulk of Uranus and Neptune, hence their "ice giant" moniker.

But a new pre-print study accepted for publication in the journal Astronomy and Astrophysics took a completely different approach. Instead of trying to build a physical model of planetary interiors from possibly flawed and biased assumptions, the authors generated a series of random models of the interior contents of Uranus and Neptune. Then, they compared those random models to a host of observational data and built a database of all models compatible with observations.

The models yielded a few expected results. Each planet is less than a quarter hydrogen and helium, which matches predictions from solar system formation models and the observed densities of the planets. The models also created layers of electrically conductive material, which can explain the magnetic fields of Uranus and Neptune.

But this agnostic approach did yield one major surprise: We may not have any idea what the interiors of Uranus and Neptune are really like.

For example, the rock-to-water ratio for Uranus varies widely, anywhere from a low of 0.04, meaning the planet is almost entirely water, to as much as 3.92, which is the complete opposite. Neptune is slightly better understood, but it could still have anywhere from as much as five times as much water as rock up to twice as much rock as water.

If that's the case, then "ice giants" may be the wrong name for these planets. Most of their bulk could be in the form of rock, potentially giving them more rocky material than even Jupiter or Saturn, even though Neptune and Uranus are much smaller than those two gas giants.

If this idea holds up, it could challenge existing models of solar system formation, as we would have to figure out a way to get enough rocky material into the outer solar system to let it accumulate onto these planets.

Only a dedicated mission to Uranus or Neptune could resolve these issues, as we need high-quality data from an orbiter to fully understand what's going on.

Ariel, one of Uranus' icy moons, may once have concealed a vast ocean more than 100 miles (170 kilometers) deep beneath its frozen crust, according to new research. The findings add to growing evidence that Uranus' moons could have been ocean worlds in the distant past.

At 720 miles (1,159 kilometers) across, Ariel is smaller than many of the moons orbiting the planets Jupiter and Saturn. Yet, its surface is exceptionally bright and unusually complex, with ancient cratered terrain lying alongside much younger, smoother plains likely shaped by cryovolcanism, a type of volcanism that happens on icy bodies

"Ariel is pretty unique in terms of icy moons," study co-author Alex Patthoff, a senior scientist at the Planetary Science Institute in Arizona, said in a statement.

Led by Caleb Strom of the University of North Dakota, the researchers set out to determine Ariel's past interior structure and orbital eccentricity — how much its orbit once strayed from a perfect circle — to explain the dramatic features visible on the moon's surface today.

To do this, the team modeled how Uranus' gravity would have stretched and squeezed Ariel over time, fracturing and reshaping the moon's icy crust.

The analysis concluded Ariel's orbit once had an eccentricity of about 0.04, roughly 40 times greater than what it exhibits today. That would have made its orbit four times more eccentric than Europa, Jupiter's icy moon that displays a fractured, geologically active surface.

The scale of Ariel's cracks and ridges, the researchers inferred, could only be explained if the crust was flexing over a liquid layer. Either Ariel harbored a massive ocean covered by a relatively thin ice shell, or a smaller ocean paired with stronger orbital stresses.

"But either way, we need an ocean to be able to create the fractures that we are seeing on Ariel's surface," Patthoff said in the statement.

This work follows a 2024 study by the same team that found evidence of a past subsurface ocean on Miranda, another of Uranus' moons. Together, the findings suggest Uranus may once have hosted multiple ocean-bearing satellites.

"We are finding evidence that the Uranus system may harbor twin ocean worlds," study co-author Tom Nordheim of Johns Hopkins University Applied Physics Laboratory, who is the principal investigator of the NASA grant supporting the research, said in the statement.

Subsurface oceans are a central focus in planetary science because they represent potential habitats for life. Liquid water provides the chemistry needed for biology, and in hidden oceans beneath ice shells, tidal heating or radioactive decay can supply the energy to sustain it, even far from the sun.

Although scientists do not yet know when Ariel's ocean formed, how long it lasted, or whether it still exists in some form, the study offers valuable insight into how such oceans evolve in the outer solar system.

The study also bolsters growing calls for a dedicated mission to Uranus. The Uranus Orbiter and Probe, recommended by the National Academies' planetary science decadal survey as NASA's highest-priority flagship mission to begin in 2023–2032, would orbit the planet for at least five years, release an atmospheric probe and explore its rings and moons in detail.

Although Congress has not yet allocated funding, scientists argue such a mission could answer major questions about Uranus' extreme tilt, its dense ring system and its potentially ocean-bearing moons. Much remains unknown about Uranus, and such a mission could be transformative — similar to how NASA's Cassini mission revolutionized knowledge of Saturn, uncovering the dynamics of its rings and revealing Titan as a world with lakes, rain and a complex atmosphere, Kathleen Mandt, a planetary scientist at The Johns Hopkins University Applied Physics Laboratory in Maryland, previously told Space.com.

So far, spacecraft have only imaged the southern hemispheres of Ariel and Miranda. The team's models may help predict what a future mission could discover in their unexplored northern regions, including additional fractures, ridges and resurfaced terrain.

"Ultimately, we just need to go back to the Uranus system and see for ourselves," Nordheim said in the statement.

The study was published in the Jan. 2026 edition of the journal Icarus.

Get ready to explore one of the most unusual planets in our solar system — Uranus, the tilted ice giant that spins on its side and keeps scientists guessing.

Add in a lopsided magnetic field and faint rings, and you've got a planet full of cosmic quirks waiting to be uncovered.

Whether you're a space trivia pro or just diving into the cosmos, Uranus is sure to surprise you.

Whether you're fascinated by planetary oddballs or just love a good challenge, this quiz will take you deep into the icy realm of Uranus.

Try it out below and see how well you score!

Astronomers using NASA's James Webb Space Telescope have discovered a newfound moon orbiting icy Uranus, the seventh planet from the sun.

The moon, known as S/2025 U1, is just 6 miles (10 kilometers) or so in diameter, which made it invisible to NASA's Voyager 2 probe during its 1986 flyby of the planet, as well as rendering it undetectable by other telescopes. But then came the powerful James Webb Space Telescope (JWST).

A team led by scientists at the Southwest Research Institute (SwRI) in Colorado made 10 different 40-minute exposures of Uranus using JWST's Near-Infrared Camera (NIRCam) in order to find the small moon. Its discovery brings the total number of known Uranian moons to 29.

S/2025 U1 is located around 35,000 miles (56,000 km) from Uranus' center. By comparison, Earth's moon orbits at an average of 238,855 miles (384,400 km) from our planet. S/2025 U1 orbits Uranus on a circular path, implying that it likely formed in its current position.

The moon orbits alongside a number of small satellites that lie inside the orbit of Uranus' largest moons — Miranda, Ariel, Umbriel, Oberon and Titania (27 of Uranus' 29 moons are named after characters found in Shakespeare plays). S/2025 UI will get an official name from the International Astronomical Union (IAU) sometime in the future.

Aside from demonstrating the revolutionary capabilities of the James Webb Space Telescope, scientists say the discovery of S/2025 U1 shows that there is still much to learn about Uranus and its complex system of moons and rings.

"No other planet has as many small inner moons as Uranus, and their complex inter-relationships with the rings hint at a chaotic history that blurs the boundary between a ring system and a system of moons," said Matthew Tiscareno of the SETI Institute in Mountain View, California, a member of the team behind this discovery, in a statement. "Moreover, the new moon is smaller and much fainter than the smallest of the previously known inner moons, making it likely that even more complexity remains to be discovered."

Uranus has 13 rings, which are divided into an inner system and a pair of outer rings. Unlike the ring systems of Jupiter and Saturn, Uranus' rings are made up of dark material and are more difficult to observe. The planet's 14 inner moons orbit among the faint inner rings, and some of these moons help hold some of the planet's rings in shape.

NASA's iconic interstellar Voyager 2 probe traveled past Uranus in January 1986, becoming the first spacecraft to do so  — and today, it remains the only one ever to have visited the distant ice giant. At the time, astronomers only knew about five moons orbiting Uranus, according to NASA.

Scientists say the capabilities of the James Webb Space Telescope will allow us to learn even more about our distant neighbors at the outer reaches of the solar system.

"Looking forward, the discovery of this moon underscores how modern astronomy continues to build upon the legacy of missions like Voyager 2, which flew past Uranus on Jan. 24, 1986, and gave humanity its first close-up look at this mysterious world," said Maryame El Moutamid, a lead scientist at SwRI. "Now, nearly four decades later, the James Webb Space Telescope is pushing that frontier even farther."

Think you know your way around the solar system?

From the scorching surface of Mercury to the icy edges of Neptune, our planetary neighborhood is full of wonders. The order of the planets isn't just trivia—it tells a story about temperature, composition, and even the possibility of life. Understanding the planets' sequence helps us grasp how the solar system formed and how it functions today.

In this quiz, you'll be challenged to put the eight planets in their correct order from the Sun.

Whether you're a seasoned space explorer or just dipping your toes into astronomy, it's time to test your cosmic knowledge!

Try it out below and see how well you score!

Scientists have found that Uranus is emitting its own internal heat — even more than it receives from sunlight — and this discovery contradicts observations of the distant gas giant made by NASA's Voyager 2 probe nearly four decades ago.

Scientists led by Xinyue Yang of the University of Houston analyzed decades of readings from spacecraft and computer models to find that Uranus emits 12.5% more internal heat than the amount of heat it receives from the sun. However, that amount is still far less than the internal heat of other outer solar system planets like Jupiter, Saturn and Neptune, which emit 100% more heat than they get from the sun.

The researchers behind this new study say Uranus' internal heat could help reveal the origins of the curious, tilted world. "This means it's still slowly losing leftover heat from its early history, a key piece of the puzzle that helps us understand its origins and how it has changed over time," Wang said in a statement.

In 1986, the iconic Voyager 2 probe flew by Uranus while headed out of the solar system and into interstellar space. A good deal of what scientists understand about the seventh planet from the sun comes from that flyby, that found that Uranus does not reveal significant internal heat.

But it turns out that we may have caught Uranus at a weird time, and some of the readings Voyager 2 collected could have been skewed by a surge in solar weather that occurred during its flyby of the planet.

By reviewing a large set of archival data and combining that with computer models, researchers now believe the internal heat emitted by Uranus could imply a completely different internal structure or evolutionary history for the planet we thought we knew. Its believed that Uranus formed around 4.5 billion years ago along with the rest of the solar system, and NASA believes it formed closer to the sun before moving to the outer solar system around 0.5 billion years later. That story, however, is now called into question by these new findings.

"From a scientific perspective, this study helps us better understand Uranus and other giant planets," Wang said in the statement. The researchers also believe this new understanding of Uranus' internal processes could help NASA and other agencies plan for missions to the distant planet.

In 2022, the National Academy of Sciences flagged a mission concept known notionally as Uranus Orbiter and Probe (UOP) as one of the highest-priority planetary science missions for the next decade. But even then, before massive budget uncertainty hit NASA and the science community in the wake of President Donald Trump's overhaul of U.S. government spending, scientists knew such an ambitious and expensive mission would be difficult to put into motion.

"There are many hurdles to come — political, financial, technical — so we're under no illusion," Leigh Fletcher, a planetary scientist at the University of Leicester in the U.K. who participated in the decadal survey process, told Space.com in 2022 when the report was published. "We have about a decade to go from a paper mission to hardware in a launch fairing. There's no time to lose."

Whether or not new research into Uranus helps boost support for such a mission, scientists are already hailing these new results as groundbreaking on their own. Study co-author Liming Li said the study of Uranus' internal heat not only helps us understand the distant, icy world better, but could also help inform studies of similar processes here on Earth, including our own changing climate.

"By uncovering how Uranus stores and loses heat, we gain valuable insights into the fundamental processes that shape planetary atmospheres, weather systems and climate systems," Li said in the statement. "These findings help broaden our perspective on Earth's atmospheric system and the challenges of climate change."

A study on Uranus' internal heat was published in the journal Geophysical Research Letters.

New data from the Hubble Space Telescope suggests that Uranus' largest moons are gathering dust — literally.

Uranus, the seventh planet from the sun and home to 28 known moons, is well known for its bizarre tilt. The planet spins almost completely on its side, an oddball orientation that twists its magnetic field into a warped and constantly shifting force, which scientists have long thought would leave visible scars on its moons by bombarding them with charged particles.

However, new Hubble Space Telescope observations of Uranus' four largest moons — Ariel, Umbriel, Titania and Oberon — show no clear signs of the expected radiation damage, Christian Soto of the Space Telescope Science Institute in Maryland, who led the analysis, told reporters on Tuesday (June 10) at the 246th American Astronomical Society (AAS) press conference in Alaska.

Based on data from NASA's Voyager 2 flyby in 1986 and decades of modeling, scientists expected the trailing hemispheres of Uranus' moons — the sides opposite their direction of travel — to be visibly darkened by radiation. The leading sides, by contrast, were expected to remain relatively brighter.

Instead, the researchers found that the two outer moons, Titania and Oberon, are darker on their leading sides, the opposite of what they had predicted. The visible darkening, they say, doesn't come from Uranus' magnetic field at all, but from dust.

Hubble's data points to a slow inward drift of dust from Uranus' distant irregular moons, which orbit between 2.5 to 13 million miles (4 to 20 million kilometers) from the planet. These outer moons are constantly bombarded by micrometeorites, which kick up particles that gradually spiral inward over millions of years, Soto said. As Titania and Oberon travel through this diffuse dust cloud, they accumulate the particles mostly on their leading sides.

"Think of driving very fast on a highway, and bugs are hitting your windshield — that's what we're seeing here," Soto said during the press briefing.

Interestingly, the inner moons Ariel and Umbriel show no significant difference in brightness between their leading and trailing sides — possibly because the drifting dust doesn't reach them, thanks to shielding by Titania and Oberon.

"Dust collection — I didn't even expect to get into that hypothesis," Richard Cartwright, a planetary scientist at the Johns Hopkins University's Applied Physics Laboratory in Maryland, said in a statement. "But you know, data always surprise you."

As for the role of Uranus' powerful magnetic field, researchers now suspect that its effects might be subtler or more complex than previously thought. It may still be interacting with the moons, but not in a way that creates strong contrasts on their surfaces.

"Uranus is weird, so it's always been uncertain how much the magnetic field actually interacts with its satellites," Cartwright said in the statement.

The findings highlight how little we still know about Uranus. Apart from Voyager 2's brief flyby nearly 40 years ago, coincidentally during a rare solar event, no dedicated mission has ever visited the planet.

To learn more, Soto's team has scheduled follow-up observations with the James Webb Space Telescope within the next year. Using infrared imaging, Webb will take a closer look at the same moons, potentially confirming whether dust, radiation or a combination of both is shaping their surfaces.

"Why do we do this?" Soto said at the briefing. "Well, Uranus is weird — so why not?"

NASA researchers got a rare chance to study Uranus' atmosphere and rings this month, when the ice giant passed between Earth and a distant star, creating a "stellar occultation."

This rare event lasted about an hour on April 7 and was only visible from western North America. The last time a bright stellar occultation of Uranus occurred was 1996, so NASA came prepared. An international team of more than 30 astronomers, led by planetary scientists at NASA's Langley Research Center in Virginia, used 18 observatories to gather data.

"This was the first time we have collaborated on this scale for an occultation," William Saunders, a planetary scientist at Langley, said in a statement.

"I am extremely grateful to each member of the team and each observatory for taking part in this extraordinary event," Saunders added. "By observing the occultation from many large telescopes, we are able to measure the light curve and determine Uranus' atmospheric properties at many altitude layers."

Related: Uranus: Everything you need to know about the coldest planet in the solar system

For example, the scientists measured the temperatures and composition of Uranus' stratosphere, the middle layer of its atmosphere. They were able to see how the stratosphere has changed since 1996, when NASA got a snapshot of Uranus' atmosphere during the last significant stellar occultation.

The data NASA just collected "could help enable future Uranus exploration efforts," agency officials said in the statement.

Uranus, which is currently about 2 billion miles (3.2 billion kilometers) from Earth, does not have a solid surface. Instead, the planet has a soft surface that's a mixture of water, ammonia and methane. Researchers call Uranus an ice giant because its interior consists largely of these fluids, all of which have low freezing points. The planet's atmosphere is mostly made up of hydrogen and helium.

"The atmospheres of the gas and ice giant planets [Jupiter, Saturn, Uranus and Neptune] are exceptional atmospheric laboratories because they don't have solid surfaces," Emma Dahl, a postdoctoral scholar at the California Institute of Technology who assisted in gathering observations from NASA's Infrared Telescope Facility in Hawaii, said in the same statement.

"This allows us to study cloud formation, storms and wind patterns without the extra variables and effects a surface produces, which can complicate simulations very quickly," she added.

NASA says Uranus will occult several dimmer stars over the next six years. The next significant Uranus occultation, which will involve a star even brighter than the one blocked out this month, will come in 2031.

Uranus just got a little more time on its hands.

A fresh analysis of a decade's worth of Hubble Space Telescope observations shows Uranus takes 17 hours, 14 minutes and 52 seconds to complete a full rotation — that's 28 seconds longer than the estimate provided by NASA's Voyager 2 spacecraft nearly four decades ago.

In January 1986, Voyager 2 became the first — and so far the only — spacecraft to explore Uranus, and with its data, astronomers pegged the ice giant's rotation period at 17 hours, 14 minutes and 24 seconds. This estimate was based on radio signals emitted by the pale turquoise planet's auroras and direct magnetic field measurements. This figure became the bedrock for calculating coordinates on the enigmatic world and mapping its surface. Scientists may need to rethink some of those maps, a new study suggests.

The initial estimate based on Voyager 2 data carried inherent uncertainties that led to a 180-degree error in Uranus' longitude, causing the orientation of its magnetic axis to become "completely lost" within just a couple of years after the spacecraft's flyby. Consequently, coordinate systems relying on the outdated rotation period quickly lost their reliability, according to the study.

To resolve this issue, a team of astronomers led by Laurent Lamy of the Paris Observatory tracked the motion of Uranus's auroras using Hubble Space Telescope data collected between 2011 and 2022. By tracking the movement of these luminous displays over a little more than a decade, the researchers were able to precisely pinpoint the planet's magnetic poles and, in turn, a better estimate of its rotational period.

"The continuous observations from Hubble were crucial," Lamy added in a statement. "Without this wealth of data, it would have been impossible to detect the periodic signal with the level of accuracy we achieved."

This approach can now be used to determine the rotation rate of any celestial object with a magnetic field and auroras, not only in our solar system but also on exoplanets and other faraway worlds, the researchers say.

The updated estimate of Uranus' rotation period has provided a much more reliable coordinate system for the ice giant, one that is expected to remain accurate for decades until future missions can offer even more refined data, according to the new study. The improved estimate could also be useful in planning future missions to Uranus, particularly in defining orbital tours and selecting suitable atmospheric entry sites, Lamy and his team wrote in the new study.

This research is described in a paper published Monday (April 7) in the journal Nature Astronomy.

An analysis of two decades of data from NASA's Hubble Space Telescope has provided fresh insights into the complex atmospheric changes on Uranus that are largely driven by the effects of the sun's radiation.

Uranus, the seventh planet from the sun, is unique for its extreme axial tilt, with its equator and orbit making nearly at a right angle — likely the result of a collision with an Earth-size object long ago. This tilt causes the planet's poles to experience prolonged, dark winters and bright summers, leading to dramatic seasonal shifts, especially at the northern and southern poles. Despite these extreme traits, however, Uranus remains one of the least understood planets in our solar system, largely because it was only visited by a single spacecraft nearly 40 years ago, Voyager 2 — and that sole encounter coincided with an exceptional solar event, further complicating our understanding of the distant ice giant.

Over the past two decades, a team led by astronomer Erich Karkoschka of the University of Arizona used the Space Telescope Imaging Spectrograph on the Hubble Space Telescope to track seasonal changes on Uranus. Because the ice giant takes just over 84 Earth years to complete one orbit around the sun, the researchers mainly got to observe the planet's northern spring as the sun moved from shining directly over the planet's equator to almost directly over its north pole by 2030.

The series of Hubble images above, seen from left to right, reveal the south polar region darkening as it enters winter shadow, while the north polar region brightens as northern summer approaches, according to a NASA statement.

Uranus's atmosphere is primarily composed of hydrogen and helium, with a small amount of methane, which gives the planet its characteristic blue-green hue by absorbing red light from the sun and reflecting blue light.

From 2002 to 2022, Karkoschka and his colleagues observed the ice giant four times — in 2002, 2012, 2015 and 2022 — documenting a richer picture of the planet's atmospheric structure than was gathered by the single Voyager 2 flyby. The recent observations suggest complex atmospheric circulation patterns on Uranus during this period, with the data most sensitive to the methane distribution indicating a downwelling in the polar regions and upwelling in other areas, according to the NASA statement.

Notably, scientists found that methane is not uniformly distributed across Uranus but is rather strongly depleted near its poles, with this depletion remaining consistent over the years.

The observations also revealed changes in aerosol concentrations, allowing scientists to map out the planet's atmospheric structure. While methane depletion and aerosol patterns remained relatively stable in the middle and low latitudes over the observed two decades, the polar regions showed more dramatic shifts.

Notably, aerosols near the north pole became brighter, especially in recent years as the planet approached its northern summer, according to the statement. These long-term observations have provided scientists with a deeper understanding of how the ice giant's atmosphere functions and reacts to changing sunlight.

They can also "serve as a proxy for studying exoplanets of similar size and composition," the Hubble team said in the statement.

The Hubble Space Telescope has spent more than thirty years providing some of the most incredible images of the known universe, but it's only for the last ten that scientists have pointed its gaze at our solar system's outer planets to observe them like never before.

For the past decade, NASA's Outer Planet Atmospheres Legacy program (OPAL) has been obtaining detailed views of the long-term changes in the skies of the four closest giants to Earth: Jupiter, Saturn, Uranus and Neptune, each home to a unique set of atmospheric variables. OPAL data has allowed astronomers to observe weather patterns and seasons of these outer planets to better understand their dynamics and changes over time.

Hubble is capable of viewing wavelengths from ultraviolet to near-infrared light, and routinely provides high-resolution images of the gas giants once a year, as each of their orbit's brings them closest to Earth. Now, with ten years of operation behind them, Hubble's OPAL team at NASA will present a decadal overview of the program's findings at the December meeting of the American Geophysical Union in Washington, D.C.

"Because OPAL now spans 10 years and counting, our database of planetary observations is ever growing. That longevity allows for serendipitous discoveries, but also for tracking long-term atmospheric changes as the planets orbit the sun. The scientific value of these data is underscored by the more than 60 publications to date that include OPAL data," said Amy Simon of NASA's Goddard Space Flight Center in a statement.

Jupiter

Jupiter is the solar system's largest planet. The gases of the planet's atmosphere churn all the way down to its core, tens of thousands of miles beneath the cloud tops. Besides its enormity, Jupiter is also known for its Great Red Spot. The unmistakable swirling red vortex on the gas giant's face is the largest storm in the solar system; a raging typhoon nearly three times the size of Earth.

Jupiter's orbit around the sun takes 12 years, allowing OPAL to have observed nearly a full Jovian year's worth of seasons. Over that time, notable changes were observed in size and shape of the Great Red Spot, as well as other atmospheric phenomena in the bands wrapping the gas giant. Seasonal changes on Jupiter are minimal, because its axial tilt of only three degrees results in only about a five percent atmospheric variability through the course of its orbit, according to NASA. (Earth, on the other hand, has an axial tilt of around 23.5 degrees, which creates the different seasons our planet experiences.)

Saturn

Saturn takes more than twice as long to circle the sun, with an orbital period lasting 29 years. The ringed giant is tilted at a much steeper 26.7 degrees, leading to much higher seasonal shifts, compared to Jupiter. Over its ten-year observation, OPAL has tracked color variation and cloud depth of Saturn's atmosphere as it cycles through the planet's changing seasons.

Hubble has also been able to observe Saturn's elusive dark ring spokes. First discovered by NASA's Voyager mission in the 1980s, these dark rings only last for two or three rotations around Saturn. Thanks to Hubble, astronomers now know the rings to be a seasonally-driven phenomenon.

Uranus

Uranus is tilted almost completely on its side, placing its rotation on nearly the same plane as the planet's orbit around the sun, which lasts a staggering 84 years.

Over the last ten years, OPAL has observed Uranus' northern hemisphere, which has faced the inner solar system for the entirety of Hubble's time in space, as it slowly tips toward the sun. Throughout its slow orbit around the sun, Uranus' north polar cap has increased in brightness as the hemisphere nears a summer solstice in 2028.

Neptune

A storm like a giant dark splotch the size of Earth's Atlantic Ocean was spotted in the atmosphere of Neptune in 2018, which Hubble followed until the storm's demise toward the planet's equator.

Another, in 2021, was observed through its formation and similar equatorial dissipation. Using OPAL data from Hubble, scientists were able to determine that the behavior of Neptune's clouds is somehow linked to the 11-year solar cycle, responsible for recent occurrences of lower-latitude northern lights on Earth.

The chance of liquid oceans hiding beneath the surface of moons orbiting Uranus has enticed NASA to begin planning a new mission that will send a spacecraft to the ice giant.

The mission is still in the conceptual planning stage. If the mission moves forward, it would be only the second in history to visit Uranus, after Voyager 2 flew by in 1986. And if it finds liquid water oceans inside Uranus's moons, we might have the answer to a profound question to aid our search for life among the stars.

Doug Hemingway, a planetary scientist at the University of Texas Institute for Geophysics (UTIG) who has developed an ocean-finding computer model for the Uranus mission, says finding liquid water oceans in Uranus's moons could mean that there are more worlds across our galaxy that hold a key ingredient for life than we know. "Discovering liquid water oceans inside the moons of Uranus would transform our thinking about the range of possibilities for where life could exist," Hemingway said in a statement.

All moons oscillate or "sway" as they orbit, but moons with oceans inside wobble more due to the sloshing liquid inside of them, so finding out how much the Uranian moons sway in orbit may give scientists the information they need to determine whether or not Uranus's moons have oceans inside of them.

These sways are measured using a spacecraft's cameras. Using this method previously, scientists figured out Saturn's moon Enceladus contains an ocean. Hemingway's computer model is designed to help the same method work on the Uranian moons.

Using theoretical calculations Hemingway came up with, the computer model created a range of scenarios that could occur when the spacecraft flies past Uranus. So, when the spacecraft gathers a measurement of a moon swaying, NASA can use it to describe characteristics of the interior ocean.

The model Hemingway produced, "could be the difference between discovering an ocean or finding we don't have that capability when we arrive," UTIG Research Associate Professor Krista Soderlund, a member of the Europa Clipper mission science team who wasn't involved with this research, said in the statement.

In October, new research published in Planetary Science Journal suggested one of Uranus's moons, Miranda, may have once held a liquid water ocean below the surface. The research drew on decades-old images from Voyager 2, which scientists sought to reverse engineer to see if they contained clues about any kind of internal structures that would explain why Miranda's exterior appeared the way it did when Voyager 2 photographed it.

The seventh planet from the sun continues to surprise us. Just last year, astronomers in Chile discovered a new moon orbiting Uranus that's only 5 miles (8 km) wide.

For sure, it was a far-reaching recommendation: The planet Uranus and its moons should be NASA's highest-priority new flagship mission for startup in the decade 2023-2032.

The proposed mission, known as Uranus Orbiter and Probe (UOP), would conduct a multiyear orbital tour to yield knowledge of ice giants in general and the Uranus system in particular, doing so through flybys and the delivery of an atmospheric probe. The payoff: "transformative, breakthrough science across a broad range of topics."

UOP was advocated within the pages of "Origins, Worlds, and Life — A Decadal Strategy for Planetary Science and Astrobiology 2023-2032." Released in 2022, that heady document came from the prestigious U.S. National Academies of Sciences, Engineering, and Medicine and was sponsored by NASA and the National Science Foundation.

Improving our knowledge

Underscoring the importance of Uranus, the Keck Institute for Space Studies (KISS) at the California Institute of Technology in Pasadena held a workshop late last year to look into how best to improve our knowledge of Uranus' internal structure in the context of a future mission that includes an orbiter and a probe.

Related: Uranus up close: What proposed NASA 'ice giant' mission could teach us

Spearheading that KISS workshop was Mark Hofstadter, a planetary scientist working at NASA's Jet Propulsion Laboratory (JPL) in Southern California. He's not solar system shy and admits Uranus is his favorite planet.

Space.com caught up with Hofstadter to discuss what exploration of Uranus — that far-flung, ice giant of a world with a mass roughly 14.5 times that of Earth — can offer. The planet has been visited only once, by NASA's Voyager 2 spacecraft during a brief flyby back in 1986.

Within the planetary community, many people are very much focused on a Uranus mission, Hofstadter said. As for the KISS study, it was focused on one aspect of the Uranus system, he said: Understanding the current structure and composition of the planet's interior, in order to learn about its formation and evolution.

"I personally believe learning about the interior is the most important reason to go to Uranus," Hofstadter said. But he also stressed that Uranus is a complex system, consisting of the planet's interior, its atmosphere, its rings and small moons, larger satellites, its magnetosphere and its interactions with the solar wind.

Thus, studying Uranus has the potential to produce transformative, breakthrough science across a broad range of topics, as the Decadal Survey pointed out, said Hofstadter.

"You could even expand that idea of 'system' to include how Uranus, over its lifetime, gravitationally altered the paths of other objects in the solar system, potentially influencing the Earth," Hofstadter added. "Every component of that system has features that violate some of our ideas about how planets work."

Ice giant

That's why the UOP's plan to put an orbiter into the middle of that system — a spacecraft equipped with a wide range of instruments, as well as a probe to enter the atmosphere — is expected to dramatically increase our understanding of our entire solar system, as well as planets that orbit other stars, Hofstadter advised.

Why does he rate Uranus' interior as the most compelling investigation for a mission?

"Of the thousands of planets we have discovered in our galaxy, most are roughly the size of Uranus and Neptune. That makes Uranus an important type of planet, and we'll apply what we learn at Uranus to all those other faraway planets we cannot study in detail," responded the JPL planetary scientist.

Complex system

Hofstadter emphasized that there are many unknowns about the composition and structure of both Uranus and Neptune. For example, scientists aren't sure if Uranus has a deep, solid region.

"We call them 'ice giants' because we originally thought they formed primarily from water ice, but recently some have argued they should be mostly rock," Hofstadter said. "Learning basic things about the interior — something we can only learn by going there with a spacecraft — will help us understand how this type of planet forms and evolves."

Related: What is Uranus made of?

Naive Earth-centric view

There's also the question of Uranus' astrobiology potential. The history of reconnoitering the outer solar system — planets beyond Mars — has been one of surprises, Hofstadter said.

Indeed, our naive Earth-centric view originally indicated that sunlight is needed to provide the energy for life, and we thought places beyond Mars would be cold, inactive, dead worlds.

"We now know that there are other ways to heat up icy objects in the outer solar system and create liquid oceans," said Hofstadter. "And we still believe liquid water is critical for life, and that the chemistry of life elsewhere might work differently than that on the Earth."

Moons of Uranus

Given that, some of the moons of Jupiter and Saturn are now considered the most likely places in our solar system to find alien life.

"We don't know enough about the Uranian moons to say whether or not they also harbor liquid oceans, but theoretical studies have shown they might," said Hofstadter. "That, combined with Voyager's images showing that some of Uranus' moons have geologically young surfaces, makes it plausible that life could exist under the icy crust of one of Uranus' moons."

Putting on his more speculative hat, Hofstadter said that some have asked if life might exist within Jupiter, Saturn, Uranus or Neptune.

"Such life would probably have a very different genesis than that of the Earth, and I don't think anyone can say if it is plausible. Nor is it clear how one might detect such life," Hofstadter said.

Weird world

Meanwhile, Earth-based work is also critical for understanding Uranus. Laboratory and theoretical studies, the KISS study explains, as well as Earth-based and space-based observations of Uranus can enable researchers to properly interpret future on-the-spot spacecraft measurements and guide what measurements a visiting craft should make, as well as where they should be made.

Uranus is the seventh planet from the sun and the third-largest world in our solar system. It is definitely and defiantly a weird world, appearing to spin sideways, rotating at a nearly 90-degree angle from the plane of its orbit.

The surprises that the Uranus Orbiter and Probe mission, should it indeed fly, will reveal at that enigmatic world will likely put scientists in a sideways spin, too.

When NASA's Voyager 2 spacecraft made its way to outer regions of the solar system in the late 80's, it noticed something odd. Both of the ice giant planets, Uranus and Neptune, lacked what's known as a "dipole magnetic field." This was in stark contrast to our own rocky world, as well as the two gas giants Jupitar and Saturn.

As dense materials near a planet's surface cool, they tend to sink into the planet's interior. On the other hand, hotter materials near the planet's interior will rise. The combination of sinking and rising materials creates convection, leading to the movement and mixing of materials within a planet. And if the interior of a planet is electrically conducting (as in, made of liquid metal or water), the convecting material — often described as a dynamo — will generate a dipole magnetic field. Think of it like a magnet with north and south poles. It is this process which generates Earth's magnetic field — the protective barrier that shields us from charged particles.

This process, however, is absent from Uranus and Neptune. So, scientists wondered: Why would that be?

For the last two decades, researchers had speculated that this was because layers of material within these worlds were unable to mix, halting any convection movement which gives rise to dipole magnetic fields in planets like our own. But, while researchers eventually agreed the problem indeed came down to the separation of layers within these worlds, the jury was still out on the compositions of these layers. Now, Burkhard Militzer, a planetary scientist at the University of California, Berkeley, thinks he has an answer.

Related: Why is Neptune's magnetic field so weird? An exotic molecule may be the answer

"We now have, I would say, a good theory why Uranus and Neptune have really different fields, and it's very different from Earth, Jupiter and Saturn," Militzer said in a statement.

Knowing this, 10 years ago, Militzer tried to simulate with computers the interiors of these worlds by cramming roughly 100 atoms of carbon, oxygen, nitrogen and hydrogen (in proportions that mirrored their abundances at the early stages on the solar system) at pressure and temperatures that mirrored their interiors. Yet, they yielded no distinct layers.

Fast forward to last year, and with the help of machine learning, Militzer was able to simulate the behavior of 540 atoms with similar ratios, and he found that layers would naturally form as the atoms were heated and compressed. "One day," he said, "I looked at the model, and the water had separated from the carbon and nitrogen. What I couldn't do 10 years ago was now happening."

"I thought, 'Wow! Now I know why the layers form: One is water-rich and the other is carbon-rich, and in Uranus and Neptune, it's the carbon-rich system that is below. The heavy part stays in the bottom, and the lighter part stays on top and it cannot do any convecting," he said.

Militzer's model predicts that underneath the 3,000-mile-thick (just over 4,800 kilometers) Uranian atmosphere sits a vast water-rich layer 5,000 miles deep (just over 8,000 kilometers). Below that, a 5,000 mile thick hydrocarbon-rich layer also exists, with a rocky core about the size of Mercury at its center.

Despite being more massive than Uranus, Neptune has a smaller total diameter and thinner atmosphere compared to its icy compatriot. However, it is likely to share similar differentiated water-rich and hydrocarbon-rich layers, with a Mars-size rocky core (providing the extra mass).

"If you ask my colleagues, 'What do you think explains the fields of Uranus and Neptune?' they may say, ‘Well, maybe it's this diamond rain, but maybe it's this water property which we call superionic,'" Militzer said. "From my perspective, this is not plausible. But if we have this separation into two separate layers, that should explain it."

Militzer hopes he might one day be able to test his hypothesis with laboratory experiments that mirror the interior conditions of these worlds. A mission to Uranus could also provide answers, Militzer says.

The paper was published on Nov. 25 in the Proceedings of the National Academy of Sciences.

Much of what we understand about Uranus comes from data gathered by NASA's Voyager 2 spacecraft. Thirty-eight years ago, this probe flew by the ice giant, providing humanity with its first close-up glimpse of the seventh planet from the sun.

However, the snapshot delivered by Voyager 2 gave us a peculiar picture of Uranus. It suggested the world has an extreme magnetosphere — at risk of simplification, a giant magnetic field around the planet — that's filled with energized particles swirling around. And, well, this just didn't jibe with scientists' knowledge of the way magnetic fields work. The problem was an observed lack of plasma in Uranus's magnetosphere, which is an expected prerequisite for the energized particles Voyager 2 saw there.

Ever since, Uranus has been viewed as an outlier — called the planet with a weird magnetosphere. But a new analysis of that original 1986 data may finally offer Uranus some reprieve. It's possible, scientists say, that something altered Uranus's magnetosphere long ago — right when Voyager 2 flew by.

That something, the research team says, was a surge in solar wind pressure, or a high uptick in charged particles (or plasma) released from the sun’s outer layer, the corona. The pressure could have drastically altered Uranus's magnetosphere, compressing it to about 20% of what it normally would be. That pressure could also lead to plasma within the magnetosphere emptying out temporarily.

Related: Some of Uranus's moons might be able to support life. Here's what a mission might reveal

So, in other words, our understanding of Uranus for the last few decades may have been highly skewed simply due to the unfortunate timing of Voyager 2's flyby.

"The spacecraft saw Uranus in conditions that only occur about 4% of the time," Jamie Jasinski, lead author of the new analysis and a space plasma physicist at NASA's Jet Propulsion Laboratory (JPL), said in a statement. “If Voyager 2 had arrived just a few days earlier, it would have observed a completely different magnetosphere at Uranus."

What is a magnetosphere?

A magnetosphere is a "bubble" around a planet that plays a big role in the planet's conditions by shielding it from both cosmic and solar particle radiation. Such particle radiation gets trapped along the magnetosphere’s magnetic field lines, which concentrate the trapped particles into radiation belts. Earth's magnetosphere, for instance, protects our atmosphere from solar winds that emanate from the sun. Without it, our atmosphere would deteriorate, which would make Earth uninhabitable.

Uranus's observed magnetosphere was puzzling for scientists because of how extremely intense its radiation belts appeared to be. They had an "intensity second only to Jupiter's notoriously brutal radiation belts," according to the statement. Yet there was no recognizable source of energized particles, so those intense radiation belts remained a mystery — until now.

When factoring in the solar wind surge theory, the picture starts making sense.

Solar wind pressure likely drove out plasma from Uranus's magnetosphere system and created a temporary condition in which the planet's magnetosphere became quite extreme. The wind would've injected charged particles (recall it's made of plasma) into Uranus's radiation belts, potentially accounting for their surprising intensity.

As a side note, the new analysis also suggests Uranus's five major moons, which were previously thought to be inert, may in fact be geologically active.

"We were searching for an explanation of its unusual behavior," JPL scientist Linda Spilker, who remembers when Voyager 2 flew by Uranus in 1986, said in the statement. "This new work explains some of the apparent contradictions, and it will change our view of Uranus once again," continued Spilker.

ASA launched Voyager 2 aboard the Titan IIIE-Centaur way back in 1977. It was the first of two probes designed to examine the outer planets. Voyager 1,essentially its twin, launched a few weeks later.

Now, Voyager 2 is nearly 13 billion miles away from Earth, and NASA is still in contact with it, receiving valuable scientific data on our solar system and beyond. A few weeks ago, NASA made the difficult decision to turn off one of Voyager 2's science instruments to conserve power so it could continue its mission.

The beloved Voyager 1 has also nabbed plenty of headlines in the last couple of months. Last year, Voyager 1 put scientists and space lovers across the world on the edge of their seats, as NASA lost contact with the venerable space explorer, only to regain it a few months later due to the intrepid work of its operators.

The research was published in the journal Nature Astronomy on Nov. 11.

Over the last few decades, planetary scientists have been steadily adding to the list of moons in our solar system that may harbor interior oceans either currently or at some point in their past. For the most part, these moons (such as Europa or Enceladus) have been gravitationally bound to the gas giants Jupiter or Saturn. 

Recently, though, planetary scientists have been turning their attention further afield, towards the ice giant Uranus, the coldest planet in the solar system. And now, new research based on images taken by the Voyager 2 spacecraft has suggested that Miranda, a small Uranian icy moon, may have once possessed a deep liquid water ocean beneath its surface. 

What's more, remnants of that ocean may still exist on Miranda today. 

When the Voyager 2 spacecraft cruised past Miranda in 1986, it captured images of its southern hemisphere. The resulting pictures revealed a smattering of different geological features on its surface, including grooved terrain, rough scarps, and cratered areas. 

Researchers, such as Tom Nordheim, a planetary scientist at Johns Hopkins Applied Physics Laboratory (APL), wanted to explain Miranda's bizarre geology by reverse engineering the surface features, working out what type of internal structures could best explain how the moon came to look like it does today. 

The team mapped the moon's various surface features, such as the cracks and ridges seen by Voyager 2, before developing a computer model to test an array of possible compositions of the moon's interior that could best explain the stress patterns seen on the moon's surface. 

The computer model found that internal composition that produced the closest match between stress patterns on the surface and the moon's actual surface geology was the presence of a deep ocean beneath Miranda's surface that existed between 100-500 million years ago. According to their models, the ocean may have once measured 62 miles (100 kilometers) deep, buried beneath 19 miles (30 kilometers) of surface ice. 

Miranda has a radius of just 146 miles (235 kilometers), which means the ocean would have taken up almost half the moon's entire body. It also means that finding such an ocean is unlikely. "To find evidence of an ocean inside a small object like Miranda is incredibly surprising," Nordheim said in a statement about the new research. 

"It helps build on the story that some of these moons at Uranus may be really interesting — that there may be several ocean worlds around one of the most distant planets in our solar system, which is both exciting and bizarre," he continued. 

Researchers speculate that the tidal focus between Miranda and other nearby moons were crucial to keeping Miranda's interior warm enough to sustain a liquid ocean. The gravitational stretching and compressing of Miranda, amplified by orbital resonances with other moons in its past, could have generated enough frictional energy to keep it warm enough from freezing over. 

Similarly, Jupiter's moons Io and Europa have a 2:1 resonance (for every two orbits Io makes around Jupiter, Europa makes one), which generates enough tidal forces to sustain an ocean beneath Europa's surface. 

Miranda eventually fell out of sync with one of the other Uranian moons, nullifying the mechanism keeping its interior warm. Researchers don't think Miranda has fully frozen over yet though, as it should have expanded, causing telltale crack on its surface. 

"We won't know for sure that it even has an ocean until we go back and collect more data," Nordheim says. 

"We're squeezing the last bit of science we can from Voyager 2's images. For now, we're excited by the possibilities and eager to return to study Uranus and its potential ocean moons in depth."

This new research was published in The Planetary Science Journal on Oct. 15.

Two NASA spacecraft have teamed up to capture direct images of Uranus. 

The Hubble Space Telescope and the New Horizons Pluto probe formed a cool tag team to investigate the mysterious seventh planet from the sun.

The views of Uranus, the coldest world in the solar system, captured by the two instruments are vastly different and are taken from different perspectives. Hubble studied the ice giant in high resolution, while New Horizons saw it as a mere smeared "blob." This actually gives astronomers a new view of the ice giant, with Hubble observing what the Uranian atmosphere is doing while New Horizons looks as well, providing vital added context. 

Though astronomers have a wealth of questions about Uranus, it is relatively well-studied compared to exoplanets beyond our solar system. The hope is that this new way of looking at Uranus could unlock a powerful new guide to what astronomers should expect when using future telescopes to image exoplanets directly, something that is notoriously tricky. 

"While we expected Uranus to appear differently in each filter of the observations, we found that Uranus was actually dimmer than predicted in the New Horizons data taken from a different viewpoint," New Horizons science team collaborator Samantha Hasler of the Massachusetts Institute of Technology (MIT) said in a statement.

Related: Some of Uranus' moons might be able to support life. Here's what a mission might reveal

Why directly image exoplanets?

Since the discovery of the first exoplanet in the 1990s, astronomers have uncovered over 6,000 of these worlds, with thousands more detected but awaiting confirmation. 

Most of these have been detected and studied by the dips in starlight they cause when they cross or "transit" the face of their parent star. Fewer are detected and investigated when they gravitationally "tug" on the star they orbit, causing a tiny "wobble" in its motion. Very few exoplanets have actually been directly imaged. 

That's because even the closest exoplanet to the solar system, Proxima Centauri b, is a whopping four light-years away. That's about 13,840 times the distance between Earth and Uranus. This means that, even when astronomers do manage to directly image an exoplanet — usually when they are just partially illuminated by their stars — it appears as little more than a tiny speck. 

Direct imaging of exoplanets is desirable because it can reveal whether they are capable of supporting life or not. It can also reveal similarities with solar system planets, which could help astronomers better understand how planets form.

That's where Uranus comes in.

Uranus is a good proxy for exoplanets for several reasons. For example, many known exoplanets are gas giants with compositions similar to that of Uranus. Additionally, New Horizons was able to examine Uranus while the ice giant was around 6.5 billion miles (10.5 billion kilometers) away from the spacecraft, allowing its Multispectral Visible Imaging Camera to capture what is called the " twilight crescent" of the planet, which is also useful for investigating exoplanets. 

While New Horizons was performing its distant observations, Hubble, in low-Earth orbit around our home planet, was only 1.7 billion miles (2.7 billion km) away from Uranus. This meant the long-serving space telescope, which launched in 1990, was able to discern the atmospheric features of the sun-facing "dayside" of Uranus, spotting Uranian clouds and storms.

"Uranus appears as just a small dot on the New Horizons observations, similar to the dots seen of directly imaged exoplanets from observatories like the James Webb Space Telescope (JWST) or ground-based observatories," Hasler continued. "Hubble provides context for what the atmosphere was doing when it was observed with New Horizons."

No cloudy days ahead for NASA's future space telescopes

One of the questions that researchers are keen to answer regarding exoplanets is whether they have clouds similar to those of solar system planets, particularly the gas and ice giants.

In the solar system, the gas giants Jupiter and Saturn and the ice giants Uranus and Neptune have dynamic atmospheres with changing cloud cover. We don't know if exoplanet gas giants have similar conditions, though.

The team used details of Uranus' clouds collected using Hubble to verify what the New Horizons spacecraft — launched in 2006 to perform a close flyby of Pluto, which it achieved in 2015 — was seeing. This revealed that brightness did not vary as the planet rotated, indicating to the team that the cloud features of Uranus were not changing as a result of the planet’s rotation.

The New Horizons observations, from an angle differing from that used by Hubble, also demonstrated that when planets are partially lit by their stars, the circumstance used to image exoplanets, they can be dimmer than predicted. It also seems from the observations that light is reflected differently by planetary atmospheres during their partially lit phase.

"These landmark New Horizons studies of Uranus from a vantage point unobservable by any other means add to the mission's treasure trove of new scientific knowledge and have, like many other datasets obtained in the mission, yielded surprising new insights into the worlds of our solar system," New Horizons principal investigator Alan Stern, of the Southwest Research Institute, said in the statement.

The team's research could help to inform studies of exoplanets performed by NASA's next major space telescope, the Nancy Grace Roman Space Telescope, or just Roman for short. Roman, set to launch in 2027, will use a device called a coronagraph to block out light from the stars that exoplanets orbit to get a better view of these worlds. 

Further into the future, NASA's Habitable World's Observatory, currently in its initial planning stages, will become the first space telescope specifically designed to hunt for biosignatures around Earth-like rocky planets.

"Studying how known benchmarks like Uranus appear in distant imaging can help us have more robust expectations when preparing for these future missions, and that will be critical to our success," Hasler concluded.

The team's results were presented this week at the 56th annual American Astronomical Society Division for Planetary Sciences meeting held in Boise, Idaho, between Oct. 6 and Oct. 10.

Over the last couple of years, planetary scientists have been increasingly calling for a mission to a largely unexplored region of the solar system: Uranus and its moons. 

Planetary scientists know that some of Jupiter's and Saturn's moons likely possess subsurface liquid-water oceans. These "ocean worlds," such as the Jovian moon Europa and the Saturnian moon Enceladus, are not in the "Goldilocks zone" — the optimal distance from a star where liquid water can exist on a world's surface — that was previously thought to be a requirement for habitability. 

Instead, researchers have been considering the possibility that life could eke out an existence inside these bodies, suspended in internal oceans heated through various mechanisms. These hypothetical life-forms might utilize chemical metabolic pathways similar to those used by life on Earth's ocean floor. 

Increasingly, the astrobiology community has been looking beyond the Jupiter and Saturn systems. They're calling for a mission to Uranus and its moons, as a number of Uranus' moons have displayed telltale signs of having internal liquid oceans and chemical compositions that could be favorable to life. 

Related: Extreme microbes in salty Arctic water could aid search for life on Mars 

Indeed, sending a spacecraft to these far-off moons could reveal clues about their habitability and the mechanisms behind the formation and evolution of these worlds, planetary scientists explained in a recent paper. 

"The most exciting prospect at the (Uranian) moons is that they could still host subsurface oceans at present. It is a low probability for some of them, so if the mission does find oceans in all/most of them, then it will help better understand what mechanisms help keep the interiors of these moons warm," says Julie Castillo-Rogez, a planetary scientist at NASA's Jet Propulsion Laboratory. 

Possible internal oceans  

Back in 2022, a team led by Castillo-Rogez reanalyzed data on five of Uranus' largest moons — Ariel, Umbriel, Titania, Oberon and Miranda — collected by NASA's Voyager 2 spacecraft as it flew by the Uranian system in 1986. When they combined Voyager 2's data with computer modeling that considered the radius and density of these moons, as well as potential sources of heat, the scientists found that four of the moons — Ariel, Umbriel, Titania and Oberon — could hold internal liquid oceans sandwiched between their cores and icy crust. 

The Uranian system's vast distance from the sun is a significant hurdle to the persistent presence of liquid oceans inside these moons. But there's another way they could get warm enough to host subsurface oceans.

"The main source of heat for these moons comes from the decay of radioactive elements, specifically potassium, uranium and thorium," Castillo-Rogez told Space.com. 

There is also geological evidence that Miranda and Ariel were subject to geologic activity —  tectonics and ice volcanoes — 100 million to 1 billion years ago. 

Put together, these signs suggest that Miranda and Ariel may have been subject to increased tidal heating, whereby the moons stretch and compress as a result of the gravitational interaction between Uranus and its moons. 

"Miranda and Ariel are close enough to Uranus that they could benefit from more tidal heating than Umbriel, Titania and Oberon," Castillo-Rogez said. "However, because tidal heating is a function of the mass of the planet — and Uranus is seven times less massive than Saturn — we don't expect the kind of spectacular volcanism process as observed at Enceladus." 

Related: Life on Enceladus? Europe eyes astrobiology mission to Saturn ocean moon

"That is, if an Enceladus-like moon was in the Uranian system, it would benefit from 50 times less heating than in the Saturnian system," she added. 

Unfortunately for the Uranian moons, the same degree of tidal heating that keeps the Jovian and Saturnian moons warm just isn't possible as Uranus does not exert the same gravitational force due to its lower mass. 

Assessing habitability  

Every decade, the U.S. National Academies of Sciences, Engineering, and Medicine polls the planetary science community to gauge priorities for the next decade of missions. The most recent such survey, conducted in 2022, showed widespread interest in a mission to the Uranian system. But what would such a mission investigate?

One area of study would be to investigate the internal thermal conditions on the Uranian moons, which play a massive role in the functioning of life as we know it. The lower limit for growth in unicellular organisms on Earth where ice is present is around minus 4 degrees Fahrenheit (minus 20 degrees Celsius). If temperatures are too cold, the possible metabolic pathways that life could use to extract energy from its environment become much more difficult. 

Known surface temperatures on the five Uranian moons of interest range from 60 Kelvin to 80 Kelvin (-213.15 degrees Celsius to -193.15 degrees Celsius), which means internal temperatures would have to be significantly warmer to be habitable. 

Another important factor is salinity. If the liquid oceans are too salty, life may not be able to survive there. Researchers have been investigating how much salt microbes that live in extreme environments on Earth can tolerate, shedding light on their limits. 

Access to chemical energy is another piece of the habitability puzzle. Any life on these moons would have to survive in the interior to avoid radiation and be close to the water. Therefore, these life-forms would need a steady source of chemical — rather than solar — energy. Life on Earth's ocean floor utilizes a form of chemosynthesis, in which organisms make use of energy released by inorganic chemical reactions to produce food. A similar process might be necessary for life to survive deep inside these moons. 

To support life as we know it, these ocean worlds would need the building blocks of life —  elements such as carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. Conversely, toxic elements, such as arsenic, would be problematic for life. 

Answers to these questions are currently out of reach, but a mission to the Uranian system would reveal clues about the potential habitability of some of these moons. Such a mission could help astronomers profile the variety of ocean worlds in our solar system and understand the processes that led to the formation and evolution of these icy oases.

"The mission to the Uranian system is not just about the moons, but is about understanding how the system (planet, rings, moons, magnetosphere) as a whole. The mission will retire many gaps in our understanding of how ice giants work, and the relationships between the moons, the planet, and the magnetosphere," says Castillo-Rogez.

Researchers may have discovered the secret ingredient of planet growth, which causes some worlds to grow rapidly in disks of gas and dust around infant stars. The model could be of specific value in understanding the growth of the solar system's giant planets.

Scientists have a fairly good understanding of how the rocky inner planets of the solar system, Mercury, Venus, Earth and Mars, formed and evolved. But the current model of collisions and gathering of asteroid-like bodies called "planetesimals" and the accretion of gas over millions of years leaves a lot to be explained when it comes to the formation of the gas giants Jupiter and Saturn and the ice giants Neptune and Uranus. 

All these giants seem to have formed too far out from the sun to grow so massive, with the growth of the outer ice giants being particularly puzzling. Jupiter is 15 times further away from the sun than our planet, and Neptune is 30 times farther away from our star than Earth. 

To help solve this planetary puzzle, a team of scientists from the ORIGINS Excellence Cluster, the Max Planck Institute for Solar System Research (MPS), and the Ludwig Maximilian University of Munich (LMU) have developed a new model of planet evolution that could account for these apparent discrepancies.

The scientists say their model is the first to incorporate all the physical processes needed for planet formation. 

"This is the first time a simulation has traced the process whereby fine dust grows into giant planets," team member Tommy Chi Ho Lau, an LMU doctoral candidate, said in a statement.

The simulation performed by the researchers suggests that disturbances in the disk of gas and dust around infant stars, called "protoplanetary disks," can trigger the rapid formation of multiple gas giants.

Their results seem to line up well with recent observations of young extrasolar planets or "exoplanets" and may reveal that giant planets can form much faster and much more efficiently than currently thought.

Related: Evidence of water found in atmosphere of mysterious 'metal god of war' exoplanet

Even giant planets start out small

Young stars are born when overdense patches form in vast clouds of interstellar gas and dust. As this gas clump accumulates material, it eventually collapses and gives birth to a "protostar."

This progenitor stellar body continues to gather material until its mass is sufficient enough to generate the pressure and temperatures at its core to trigger the nuclear fusion of hydrogen to helium, the process that defines a star's "main sequence" lifetime.

Material that remains in this newborn star's prenatal cocoon flattens out as it swirls around the star, creating a protoplanetary disk. As the name suggests, it is from this disk of gas and dust that the planets emerge.

The team's model suggests that millimeter-sized dust particles accumulate aerodynamically in the turbulent protoplanetary disk. This perturbation traps dust and prevents it from heading toward the central infant star. This spurs an accumulation of planetary "building blocks" in a relatively small region of the protoplanetary disk. These are just the conditions needed for a planet to form.

"When a planet gets large enough to influence the gas disk, this leads to renewed dust enrichment farther out in the disk," Til Birnstiel, Professor of Theoretical Astrophysics at LMU and member of the ORIGINS Cluster of Excellence said. "In the process, the planet drives the dust – like a sheepdog chasing its herd – into the area outside its own orbit."

This could lead to the formation of planets as far away from their star as 200 times the distance between Earth and the sun, more than enough to explain the formation of the solar system's giant planets around 4.5 billion years ago.

The team's model also implies that the solar system stopped birthing planets after Neptune simply because planetary building blocks had been exhausted.

The results generated by the team's simulations seem to match observations of young planetary systems made by the Atacama Large Millimeter/submillimeter Array (ALMA), a collection of 66 radio antennas located in northern Chile.

Not only could this research help us understand the birth and evolution of giants in our own planetary system, but it could also give astronomers hints as to the diversity of exoplanets in the wider Milky Way galaxy.

The team's research was published in the journal Astronomy & Astrophysics.

Using the James Webb Space Telescope (JWST), astronomers discovered that Ariel, a moon of Uranus, could be hiding in a buried liquid water ocean. 

The discovery could supply an answer to a mystery surrounding this Uranian moon that has perplexed scientists: the fact Ariel's surface is covered with a significant amount of carbon dioxide ice. This is puzzling because at the distance Uranus and its moons exist from the sun, 20 times further out from the sun than Earth, carbon dioxide turns to gas and is lost to space. This means some process must refresh the carbon dioxide at the surface of Ariel.

Previous theories have suggested this happens as a result of interactions between Ariel's surface and charged particles trapped in Uranus' magnetosphere that provide ionizing radiation, breaking down molecules and leaving carbon dioxide, a process called "radiolysis."

However, new evidence from the JWST suggests the source of this carbon dioxide could come not from outside Ariel but from its interior, possibly from a buried subsurface ocean.

Related: 'Traffic jams' around Uranus could solve the mystery of its weak radiation belts

Because chemical elements and molecules absorb and emit light at characteristic wavelengths, they leave individual "fingerprints" on spectra. The team behind this discovery used the JWST to gather spectra of light from Ariel, which helped them paint a picture of the chemical makeup of the Uranian moon. 

Comparing this to simulated spectra from a chemical mix in the lab here on Earth revealed to the team that Ariel has some of the most carbon dioxide-rich deposits in the solar system. Not only did this add an extra 10 millimeters (0.4 inches) of thickness to the ice on the side of the tidally locked Ariel that permanently faces away from Uranus, but it also revealed clear deposits of carbon monoxide for the first time.

"It just shouldn't be there. You've got to get down to 30 kelvins [minus 405 degrees Fahrenheit] before carbon monoxide's stable," team leader Richard Cartwright from the Johns Hopkins Applied Physics Laboratory (APL) said in a statement. "The carbon monoxide would have to be actively replenished, no question."

That's because Ariel's surface temperature is, on average, around 65 degrees Fahrenheit (18 degrees Celsius) warmer than this key temperature.

Cartwright acknowledges that radiolysis could account for some of this replenishment. However, observations from Voyager 2's 1986 flyby of Uranus and its moons and other recent findings have suggested that the interactions behind radiolysis could be limited because Uranus' magnetic field axis and the orbital plane of its moons are offset from each other by about 58 degrees.

That means that the majority of the carbon/oxygen compounds seen on Ariel's surface could be created by chemical processes in a liquid water ocean trapped under ice on Ariel.

Cool customer Ariel may have a volcanic temper

Once created in the seep water ocean of Ariel, these carbon oxides could then escape through cracks in the icy shell of the Uranian moon or could even be explosively ejected by powerful eruptive plumes.

Scientists have suspected for some time that the cracked and scarred surface of Ariel may indicate the presence of active cryovolcanoes, volcanoes that erupt plumes of icy slush rather than lava. These plumes could be so powerful that they launch material into Uranus's magnetic field.

The majority of the cracks and grooves seen on the surface of Ariel are located on the side of the moon that faces away from Uranus. If carbon dioxide and carbon monoxide are leaking from these features to the surface of the Uranian moon, this could explain why these compounds are found in greater abundance on this trailing side of the icy body.

The JWST also picked up more chemical evidence of a subsurface liquid water ocean. Spectral analysis hinted at the presence of carbonite minerals, salts created when rock meets and interacts with liquid water.

"If our interpretation of that carbonate feature is correct, then that is a pretty big result because it means it had to form in the interior," Cartwright explained. "That's something we absolutely need to confirm, either through future observations, modeling, or some combination of techniques."

Uranus and its moons haven't been visited by a spacecraft since Voyager 2 almost four decades ago, and this wasn't even the spacecraft's primary mission. In 2023, the Planetary Science and Astrobiology decadal survey emphasized the need to prioritize a dedicated mission to the Uranian system.

Cartwright believes such a mission would present an opportunity to collect valuable information about Uranus and Neptune, the solar system's other ice giant. Such a mission could also deliver vital data about the other potentially ocean-bearing moons of these systems. This information could then be applied to extrasolar planets, or "exoplanets," beyond the solar system.

"All these new insights underscore how compelling the Uranian system is," team member and NASA Applied Physics Laboratory scientist Ian Cohen said. "Whether it's to unlock the keys to how the solar system formed, better understand the planet’s complex magnetosphere, or determine whether these moons are potential ocean worlds, many of us in the planetary science community are really looking forward to a future mission to explore Uranus."

The team's research was published on Wednesday (July 24) in The Astrophysical Journal Letters.

Skwatchers will see both Mars and Uranus in the same field of view today using a pair of binoculars as the two planets make a close approach.

Mars and Uranus shared the same right ascension (the celestial equivalent of longitude) in the dawn sky yesterday (June 15), in an arrangement called a conjunction. The pair will still be close together in the predawn sky early on Tuesday (July 16), rising in the east around 2:30 a.m. (0630 GMT). 

The pair should be comfortably visible through a pair of binoculars, according to In-The-Sky.org. Mars and Uranus will be in the constellation of Taurus, the Bull. The planets will be visible in the dawn sky starting at nearly 4 hours before the sun rises. If you use optics such as binoculars or a telescope to view the arrangement, take care not to point them at the sun as it rises, as it could cause permanent damage to your eyes.

Mars will have a magnitude of 0.9, while Uranus will have a magnitude of 5.8. The planets will be most visible in the pre-dawn sky, reaching an altitude of around 47 degrees above the eastern horizon before they fade from view as dawn breaks at around 6:30 a.m. local time.

Related: Night sky, July 2024: What you can see tonight [maps]

While the pair will be too widely separated to fit within the field of view of a telescope, the two planets will be visible together through a pair of binoculars. To spot the planetary pair, viewers can use Mars as a beacon to locate the fainter, blue-green Uranus, which will be located to the upper left of the Red Planet. 

During their close approach, Mars will pass only 0.55 degrees (which is roughly the diameter of the full moon) south of Uranus. The pair will appear in close proximity in the night sky through July 23, as Uranus shifts farther to the upper right of Mars.

If you want to get a closer look at the planets of the night sky take a look at our guides to the best telescopes and best binoculars. 

And if you want to photograph the pair, we have tips for how to photograph the planets, as well as guides to the best cameras for astrophotography and best lenses for astrophotography.

Editor's Note: If you snap an image of the close approach between Uranus and Mars and would like to share it with Space.com's readers, send your photo(s), comments and your name and location to spacephotos@space.com.

Scientists may have solved a lingering mystery surrounding the ice giant Uranus and its weak radiation belts. It's possible the belts' weakness is linked to the planet's curiously tilted and lopsided magnetic field; the field could be causing "traffic jams" for particles whipping around the world.

The mystery dates back to Voyager 2's visit to Uranus in January 1986, far before the probe left the solar system in 2018. The spacecraft found that Uranus' magnetic field is asymmetric and tilted roughly 60° away from its spin axis. Additionally, Voyager 2 found that the radiation belts of Uranus, consisting of particles trapped by this magnetic field, are about 100 times weaker than predicted. 

The new research, based on simulations made using Voyager 2 data, suggests these two strange aspects of the ice giant are related.

"It has a magnetic field like no other in the solar system. Most planets that have strong intrinsic magnetic fields, like Earth, Jupiter and Saturn. They have a very 'traditional' magnetic field shape, which is known as a dipole," lead author Matthew Acevski told Space.com. "This is the same magnetic field shape as you would expect from your everyday bar magnet. At Uranus, this is not the case; Uranus' field is highly asymmetric — and it becomes increasingly so closer to the planets’ surface."

Related: Uranus and Neptune are actually similar blues, 'true' color images reveal

Acevski explained this research highlights how Uranus' magnetic asymmetry warps the structure of the planet's proton radiation belts, especially near the region passed by Voyager 2. 

"My hypothesis was that the magnetic asymmetry was warping the proton radiation belts, forming regions around the planet where the radiation belts were more compressed," Acevski said, "and, thus, with stronger intensity; other regions where they were more spread out, leading to weaker intensity. 

"If Voyager 2 flew through a region where the radiation belts were more spread out, that could explain its observations of weaker-than-expected proton radiation belts."

A solar system anomaly

The coldest planet in the solar system and the seventh planet from the sun, Uranus is odd among the other worlds of our planetary system. The ice giant rolls around like a cosmic ball, tilted in one direction at a 97-degree angle from the plane of its orbit. That means, when it rotates, it does so kind of "sideways." It's the only solar system planet that does this. 

The tilt, which is believed to be the result of a collision with an Earth-size object in the distant past, causes Uranus to have the most extreme seasons in the solar system, with a winter that lasts 21 years. Completing an orbit once every 84 Earth years, Uranus is also only one of two planets in the solar system (the other is Venus) that rotates around the sun in the opposite direction to all the other planets. 

About four times wider than Earth and located around 19 times as far from the sun as our planet sits, Uranus is looped by 13 faint rings and at least 28 moons. Uranus also has auroras, similar to the northern and southern lights of Earth, but because of the planet's tilted magnetic field, these don't appear over its poles as they do over our planet, Jupiter and even Saturn.  

Like with all planets that have magnetic fields, there are trapped charged particles around Uranus, creating radiation belts — but why these radiation belts seem so weak has remained a puzzle for five decades.

The team's simulation abandoned the idea that Uranus' magnetic field acts as a dipole and used a more complex quadrupole magnetic field to replicate its lopsided nature.

This revealed that particles accelerate and decelerate as they pass through regions of different field strengths. The particles' changes in speed cause them to bunch up in some regions and become more dispersed in others. This effect only appears when a single, complex quadrupole magnetic field is factored into the simulation, which is why it had never been seen before. 

"We found that Uranus' magnetic asymmetry could result in regions around the planet where the protons drift slower and are more compressed and other regions where they drift faster and are more spread out," Acevski said. "This is analogous to how traffic jams form on a ring road. When cars travel slower, it causes more dense traffic; if cars travel faster, the traffic is more spread out."

Acevski and colleagues theorize that when Voyager 2 visited Uranus, it passed through a weak area of the ice giant's radiation belt.

"We projected Voyager 2's trajectory onto this profile and found that the spacecraft did, in fact, fly through a region of 'fast drift,' which would imply it should have observed lower than normal proton radiation belt intensity," Acevski said. "It is important to note that our particle simulations show this result accounts for a maximum variation of approximately 20% of the proton intensity around the planet."

That means the team's model can't fully account for the 100 times lower intensity observed by Voyager 2.

"It is possible that whatever primary effect did cause these much weaker proton radiation belts could have been compounded by this effect that we found," Acevski continued. "We were extremely surprised by the results. It is amazing to see how much of an influence magnetic asymmetry can have on radiation belt structure. This is something that was not previously known."

Acevski pointed out that the results obtained by himself and the team could help inform future spacecraft missions to Uranus. Thus far, Voyager 2 is the only spacecraft to visit the ice giant. This means direct data about the world is extremely limited.

Plans are underway at NASA to launch a mission to Uranus as soon as 2030. Such a mission could help experimentally verify the conclusion of this simulation.

"What we need to verify these simulations is a flagship spacecraft mission to Uranus to get new, in-situ measurements of the planet over the course of several years rather than just a few hours as Voyager 2 did," Acevski said. "A new mission could also allow us to uncover new physics that we couldn't even predict with simulations. 

"As this is a planet with a magnetic field that we have never seen before, it is entirely possible that completely new phenomena are found, which would broaden our understanding of planetary science."

Acevski certainly is not finished with this strange solar system world yet. The ice giant is a particular fascination for the researcher.

"Uranus presents a unique challenge to science, one which I am finding great enjoyment in tackling. It is truly fascinating how much you can uncover with so little data, and we are quite literally only scratching the surface," Acevski concluded. "As of today, there are not many people researching the icy giant planets, Uranus and Neptune, despite the fact that they exhibit such strange features, particularly in their magnetic fields, and so drawing attention to the strange phenomena that can occur there is a very exciting prospect to me."

The team's research was published in June in the journal Geophysical Research Letters.

Humanity has lost an interstellar pioneer.

Ed Stone, who served as the project scientist for NASA's groundbreaking Voyager mission from 1972 to 2022, died on Sunday (June 9) at the age of 88.

"Ed Stone was a trailblazer who dared mighty things in space. He was a dear friend to all who knew him, and a cherished mentor to me personally," Nicola Fox, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington, said in NASA's obituary for Stone, which the agency posted on Tuesday (June 11). 

"Ed took humanity on a planetary tour of our solar system and beyond, sending NASA where no spacecraft had gone before," Fox added. "His legacy has left a tremendous and profound impact on NASA, the scientific community, and the world. My condolences to his family and everyone who loved him. Thank you, Ed, for everything."

Related: Going interstellar: Q&A with Voyager project scientist Ed Stone

Voyager launched twin probes on a "grand tour" of the solar system's giant planets in 1977. The two spacecraft made many discoveries in our cosmic backyard — finding intense volcanism on the Jupiter moon Io and 10 new moons of Uranus, for example — and then kept on flying, into exciting and unexplored realms.

In 2012, Voyager 1 popped free of the heliosphere, the huge bubble of charged particles and magnetic fields that the sun blows around itself, becoming the first human-made object ever to reach interstellar space. Voyager 2, which took a different path and is moving slightly more slowly than its partner, followed suit in late 2018.

Both Voyagers remain operational today, studying the exotic environment between our star and the next. Voyager 1 is currently more than 15 billion miles (24 billion kilometers) from home, and its twin is about 13 billion miles (21 billion km) into the void. That's about 162 and 136 Earth-sun distances (or astronomical units), respectively.

"It has been an honor and a joy to serve as the Voyager project scientist for 50 years," Stone said in a NASA statement in October 2022, when he announced his retirement from the role.

"The spacecraft have succeeded beyond expectation, and I have cherished the opportunity to work with so many talented and dedicated people on this mission," he added. "It has been a remarkable journey, and I'm thankful to everyone around the world who has followed Voyager and joined us on this adventure."

Related: Voyager: 15 incredible images of our solar system (gallery)

Stone was born on Jan. 23, 1936, in Knoxville, Iowa, according to NASA's obituary. His father was a construction superintendent who loved showing his son how to take things apart and put them back together — and young Ed was an eager student.

"I was always interested in learning about why something is this way and not that way," Stone said in an interview in 2018, according to NASA's obituary. "I wanted to understand and measure and observe."

He studied physics in junior college, then went to the University of Chicago for graduate school, where he helped build science instruments for spacecraft — still a very young field at this stage.

"The first he designed rode aboard Discoverer 36, a since-declassified spy satellite that launched in 1961 and took photographs of Earth from space as part of the Corona program," NASA wrote in the obituary. "Stone's instrument, which measured the sun's energetic particles, helped scientists figure out why solar radiation was fogging the film and ultimately improved their understanding of the Van Allen belts, energetic particles trapped in Earth's magnetic field."

Stone became a post-doctoral fellow at the California Institute of Technology (Caltech) in 1964 and soon began working on NASA missions. Over the years, he served as the principal investigator or a science instrument lead on nine different agency missions and a co-investigator on five others, according to the agency. 

Stone also served as director of the Jet Propulsion Laboratory (JPL) in Southern California — the agency's lead center for robotic planetary exploration — from 1991 to 2001. That stretch saw some major milestones, including the landing of NASA's first-ever Mars rover, Sojourner, in 1996 with the Pathfinder mission and the launch of the Cassini-Huygens mission to Saturn (a joint effort with the European Space Agency) in 1997.

"Ed will be remembered as an energetic leader and scientist who expanded our knowledge about the universe — from the sun to the planets to distant stars — and sparked our collective imaginations about the mysteries and wonders of deep space," JPL Director Laurie Leshin, who's also the vice president of Caltech, said in NASA's obituary.

"Ed’s discoveries have fueled exploration of previously unseen corners of our solar system and will inspire future generations to reach new frontiers," Leshin added. "He will be greatly missed and always remembered by the NASA, JPL and Caltech communities and beyond."

Stone's colleagues have repeatedly noted his commitment to science education and communication, his genuine desire to help tell the world about scientific results in a manner both accurate and engaging.

I can attest to this commitment, for I witnessed it first-hand on multiple occasions. Despite being a very busy man, Stone was open and available to the media; he took our phone calls and stayed on after press conferences to answer more and more of our questions.

And he was unfailingly nice, polite and patient in all of these interactions. I didn't know Ed Stone well, but I could tell he was a good man. And I, like countless others, will miss him.

In the depths of our solar system — a realm where chemistry meets speculation — scientists have reported the possible existence of a molecule known as aquodiium, an elusive cousin of the ammonium ion. If true, that could explain oddities in Neptune and Uranus’ magnetic fields.

This is a big deal because stable aquodiium, which consists of four atoms of hydrogen and one atom of oxygen (H4O2+), has never been observed before due to the high energy barrier involved in adding a second proton to the molecule hydronium (H3O+), which is how aquodiium must be formed. Hydronium, however, is a bit easier to create. It forms through the fundamental process of adding a proton to water. The jump from hydronium to aquodiium is the hard part.

Related: 3 tiny new moons found around Uranus and Neptune — and one is exceptionally tiny

However, with the help of advanced computer models, researchers have pinpointed a potential habitat for aquodiium: the extreme pressures found in the cores of ice giants Uranus and Neptune. And, importantly, its presence in this intense, icy environment may help explain the planets' unusual magnetic fields — weirdly, they're both highly tilted relative to their axis of rotation and significantly offset from the planets' centers. 

Could aquodiium be to blame?

Peculiar chemistry for peculiar worlds

Due to having a similar size and mass, the cores of Neptune and Uranus are almost identical. Both have rocky cores like Jupiter and Saturn, but unlike their larger neighbors, their internal pressures are not sufficient to convert molecular hydrogen into an electrically conducting liquid metal. Instead, a large mantle of icy water and ammonia forms about 12,427 miles (20,000 kilometers) below these worlds' surfaces.

This is where things get interesting: the study's authors suggest the planets' unusual magnetic fields could be generated by ions acting as charge carriers. Ions are atoms or molecules with a net electrical charge resulting from the loss or gain of one or more electrons. These ions pertaining to Uranus and Neptune's magnetic fields don't have to exist solely as standalone protons but could also include hydronium, ammonium — and aquodiium.

In chemistry, a molecule typically exists in its lowest energy form, known as the ground state. This is because nature tends to follow the path of least resistance, and the ground state minimizes factors such as bond strain, meaning atoms within the molecule are connected at less-than-ideal angles, and electrostatic repulsion, where charged atoms or groups within the molecule repel one another. The challenge with forming aquodiium (H4O2+) lies in the increased electrostatic repulsion and strain that occur when adding a second proton to the hydronium ion — it's like trying to bring together two positively charged magnets. 

When a proton is added to water to form hydronium, those two factors are more easily overcome; the resulting molecule has a positive charge localized on only one of the oxygen atoms, with the hydrogen atoms arranged in a stable geometry around the oxygen atom in the center. To go from this situation to aquodiium, you'd need to adding a second proton to the structure — but that would increase the amount of positive charge in the molecule, leading to significant electrostatic repulsion between both the positively charged protons and disrupting the hydronium's existing molecular structure, creating strain.

Under normal conditions, these factors don't allow stable aquodiium to form. The only way it'd be possible would be if enough energy were present in the reaction to force the molecule to come together anyway, amid all the strain, repulsion, and other complications not even discussed. We don't have that kind of energy on Earth. However, under the extreme conditions in Uranus and Neptune, there may indeed be enough energy.

The scientists reported that aquodiium appeared as a plausible outcome in their simulations specifically because the very high pressures found in these worlds encourages the bonding of oxygen and hydrogen ions such that aquodiium can be stabilized. And if stable aquodiium lurks in these planets, well, we may finally be on the road to decoding where they get their odd magnetic fields.

The study was published in May in the journal Physical Review B.

Astronomers have long believed that the ice giants Uranus and Neptune are rich in frozen water. However, a new study suggests they may also have tons of methane ice.

The findings could help solve a puzzle about how these icy worlds formed.

Much about Uranus and Neptune remains unknown. These ice giant worlds have had just a single spacecraft visitor, Voyager 2, which flew past them in the 1980s. As a result, scientists have only a hazy idea of the ice giants' compositions — for example, that they contain significant amounts of oxygen, carbon and hydrogen.

Related:The rings of Uranus are being held back by its pesky moons

To learn more about what Uranus and Neptune are made of, astronomers have devised models that match the physical properties that Voyager 2 and Earth-based telescopes have measured. Many models assume the planets have a thin hydrogen and helium envelope; an underlying layer of compressed, superionic water and ammonia; and a central rocky core. (The water is what gives them their "ice giant" tag.) Some estimates suggest Uranus and Neptune may each have 50,000 times the quantity of water in Earth's oceans.

But the authors of the new study say these models ignore the way the ice giants formed. As Uranus and Neptune coalesced from the dust cloud surrounding the young sun, they gobbled up, or accreted, objects called planetesimals. The team says these planetesimals resemble present-day comets such as 67P/Churyumov-Gerasimenko, which originate in the Kuiper Belt, the doughnut-shaped region of icy bodies beyond the orbit of Neptune.

Unlike the supposedly water-rich ice giants, though, a large fraction of these planetesimal-like objects are rich in carbon. So "how is it possible to form an icy giant from ice-poor building blocks?" said Uri Malamud, the study's lead author and a planetary scientist at Technion – Israel Institute of Technology.

To resolve this apparent paradox, Malamud and his co-authors built hundreds of thousands of models of Uranus' and Neptune's interiors. The algorithm they used "starts matching a suitable composition for the surface of the planet, and it gradually works its way deeper into the central point of the planet." They considered several chemicals, including iron, water and methane, the main component of natural gas. Then, they tried to determine which model most resembled the actual ice giants in traits such as radius and mass.

Of the various models they built, the astronomers found that those with methane fit their criteria, with the methane — either in solid chunks or, given the pressure, in a mushy state — forming a thick layer between the hydrogen-helium envelope and the water layer. In some models, methane accounted for 10% of the planet's mass.

The team published their results, which have not yet been peer-reviewed, to the preprint server arXiv in March.

This methane holds the key to resolving the ice paradox. The ice could have formed when hydrogen in the growing planets chemically reacted with the carbon in the planetesimals the planets accreted, the researchers said. Such reactions happen under high temperatures and superhigh pressures — millions of times the air pressure we experience on Earth. These are the exact conditions scientists think existed in the developing planets.

The findings could provide greater insight into these little-understood planets, although verifying if they are actually rich in methane would be challenging, Malamud said. That would be a goal for one of several proposed missions from NASA and other space agencies that aim to explore Uranus.

Astronomers have discovered two tiny moons orbiting Neptune and one circling Uranus, bringing the number of their known moons to 16 and 28 respectively.

Uranus' new moon, the first detected around the ice giant in over two decades and possibly the smallest of its ilk, is just 5 miles (8 kilometers) wide; it takes 680 days to complete one orbit around Uranus. In comparison, one Mars' moons named Deimos, considered to be among the tiniest known moons in our solar system, is 8 miles (13 km) wide. 

The new moon of the blue-green planet is currently referred to as "S/2023 U1" while it awaits being named for a Shakespearean character, according to a statement by Carnegie Institution for Science (or Carnegie Science). 

The brighter of Neptune's two new moons is provisionally named "S/2002 N5." At 14 miles (23 km) wide, this newly discovered satellite seems to be in a 9-year orbit around Neptune. The fainter moon, currently assigned the name "S/2021 N1," is 8.6 miles wide (14 km) and circles Neptune once every 27 years. Both Neptunian moons will be assigned permanent names based on sea gods and nymphs in Greek mythology.

Related: Uranus and Neptune are actually similar blues, 'true' color images reveal

The three new moons were announced Friday (Feb. 23) by the International Astronomical Union's Minor Planet Center, a Massachusetts-based scientific body responsible for designating planets, comets and moons in our solar system. 

The discovery was made using observatories in Hawaii and Chile by Scott Sheppard, a staff scientist at Carnegie Science, in collaboration with Marina Brozovic and Bob Jacobson of NASA's Jet Propulsion Laboratory (JPL), David Tholen of the University of Hawaii, Chad Trujillo of Northern Arizona University and Patryk Sofia Lykawa of Kindai University.

The new moons are "the faintest ever found around these two ice giant planets using ground-based telescopes," Sheppard said in Friday's statement. "It took special image processing to reveal such faint objects."

He first detected the new Uranian moon in November of last year while using Chile's Magellan telescopes. A month later, follow up observations combined with JPL scientists' predictions of a possible orbit for the new moon confirmed the find.

The two new residents in Neptune's moon system were first seen in September 2021. After the orbit of the brighter of the two natural satellites, S/2002 N5, was confirmed, "it was traced back to an object that was spotted near Neptune in 2003 but lost before it could be confirmed as orbiting the planet," said Sheppard.

Determining the orbit of the fainter Neptunian moon "required special observing time under ultra-pristine conditions" with Europe's Very Large Telescope in Chile and Gemini Observatory in Hawaii, according to the statement.

Using these telescopes, Sheppard and colleagues clicked a series of five-minute exposures over three-to four-hour periods. These short-burst images were later “layered” such that the three newfound moons came into clearer view.

All three moons have egg-shaped orbits highly inclined to the plane of their respective ice giants. This implies they did not birth around their host planet but were instead gravitationally seized later on.

The moon makes for a handy guide to locate Uranus in the night sky tonight (Jan. 19).

The elusive Uranus, the second-most distant planet in our solar system, will be just a few degrees away from the moon, making tonight an excellent time to get a glimpse of the ice giant.

To see Uranus beside the moon, look high in the eastern sky at sunset. Uranus will appear as a blue-green orb, found to the moon's lower right (or celestial south-southwest). Binoculars with high magnification should be able to resolve it, but a telescope will make it much easier.

During the meetup with Uranus, the eight-day-old moon will be 69.9% illuminated as it waxes towards the first full moon of 2024, January's Wolf Moon, which occurs on Jan. 25. 

Related: Night sky, January 2024: What you can see tonight

Uranus will be fairly dim at magnitude 5.7, while the moon will be quite bright and impossible to miss, shining at magnitude -10.94. (Negative numbers indicate particularly bright objects in the night sky.)

The brightness of the moon means Uranus will be easier to see if you hide the moon just beyond the upper edge of your binoculars' field of view, or if you use a telescope for an up-close look. While you're gazing up there, find the medium-bright star Botein (Delta Arietis), which will appear between the moon and Uranus. It can also be used to help guide you to Uranus when the moon isn't nearby as it will be tonight.

The moon and Uranus will appear in the Taurus constellation, which contains the skywatching favorite M45, the Pleiades star cluster. Nearby will also be Jupiter, which will be in between the aquatic constellations of Cetus, the Whale, and Pisces, the Fishes.

If you're hoping to catch a close-up look at the moon, Uranus or anything in the night sky, be sure to read our guides on the best telescopes and best binoculars to help you find the optics that suit your needs and budget.

And if you want to take your own photos of the moon, Uranus or any other amazing sights in the night sky, check out our guides on how to photograph the moon and how to photograph the planets, as well as our breakdowns of the best cameras for astrophotography and best lenses for astrophotography.

Editor's Note: If you snap an image of the moon beside Uranus and would like to share it with Space.com’s readers, send your photo(s), comments, and your name and location to spacephotos@space.com.

The world of astronomy has already offered a pretty fascinating start to 2024. In just the first five days of the year, we've seen incredible discoveries like the true colors of Neptune and Uranus as well as a massive cyclone raging on a distant exoplanet thanks to the trusty Hubble Space Telescope. But things are only going to ramp up over the next week. By a lot. 

From Jan. 7 to Jan. 11, the 243rd meeting of the American Astronomical Society will convene in the vibrant city of New Orleans, Louisiana. 

Thousands of scientists specializing in an absolutely incredible array of subjects ranging from dark matter mysteries to star explosions and the search for habitable exoplanets to the technology required to propel spacecraft across the solar system will gather in one area. They'll get ready to announce some of the best and brightest studies they've been working on; meanwhile, they'll be figuring out how to get even bigger and brighter with their next by listening to wild ideas, strange contradictions and telescopic achievements their colleagues will lay out. Some have even called this event the "Super Bowl of Astronomy." 

Related: The Magellanic Clouds must be renamed, astronomers say

NASA will be there too, to offer updates on major missions like the trailblazing, $10 billion James Webb Space Telescope and the upcoming, highly anticipated, Habitable Worlds Observatory. According to a statement released on Jan. 5, NASA will also be discussing the 2024 total solar eclipse, which will take place on April 8, the Transiting Exoplanet Survey Satellite (TESS), the Nancy Grace Roman Telescope currently under construction and even its scientific balloon program.

"Experts will discuss new research from NASA missions at the 243rd meeting of the American Astronomical Society (AAS) on topics ranging from planets outside our solar system to fleeting, high-energy explosions in the universe," the agency said in the statement.

All NASA press conferences will be streamed for the public to view on AAS's Press Office YouTube channel; other conferences during the meeting will be found there as well. After the meeting concludes, the streams will be available to view on an online archive provided by the organization. You'll notice that this archive includes a wealth of presentations from previous years as well.

Beyond NASA, teams from other iconic space facilities, current and upcoming, are scheduled to speak, too. Members of the Rubin Observatory, for instance, are expected to let everyone know how things are going with their efforts to discover tens of billions of galaxies once its construction is complete in Chile. But, as we'd mentioned, perhaps the most interesting and hopefully mind-blowing presentations will be coming from researchers speaking during the event. 

Though we don't have a ton of information yet on each of those talks, we're able to see some of the study headlines. And they look quite intriguing. For instance, Jan. 8 is poised to bring us an update on a "dark galaxy," the origins of "odd radio circles," and a "famous exploded star in its best light." Jan. 9 appears to have information concerning an exoplanet's tail-like escaping atmosphere and a highly distant fast radio burst seen by the Hubble Space Telescope. Jan. 10 has something about a "supernova imposter" on its schedule and Jan. 11 beholds an entire category of presentation dubbed "Oddities in the Sky." This honestly barely scratches the surface. You can have a look at the full list of presentations here.

Briefings are scheduled to begin between (and including) Jan. 8 to Jan. 11 at 10:15 a.m. CST (11:15 a.m. EST) and then again at 2:15 p.m. CST (3:15 p.m. EST). During the week, you can follow along with Space.com as we bring you some of the AAS's 243rd meeting highlights.

In the summer of 1989, from a remote expanse of our solar system where sunlight is merely a tepid glow, NASA's Voyager 2 spacecraft radioed to Earth humankind's very first images of Neptune. The pictures revealed the sun's outermost planet was a stunning, deep blue orb. In contrast, Uranus, Neptune's planetary neighbor and the first to be discovered with a telescope, appeared noticeably paler.

Both seemingly twin worlds have a lot in common. They're roughly the same size, almost equally massive and are both enveloped with deep atmospheres made of similar materials. So why were the two orbs different shades of blue? This is a question that has puzzled scientists for decades. 

Now, however, a fresh analysis of Voyager 2's images show both ice giants are in fact a similar shade of greenish blue, which is the "most accurate representation yet" of the planets' colors, the new study finds.

Related: The rings of Uranus look positively festive in epic James Webb Space Telescope holiday photo

How could we miss this?

Back in the late 1900s, the images Voyager 2 recorded of Uranus and Neptune were in single colors combined to create composite images that showed the planets to be cyan and azure, respectively. While Uranus' published pictures were processed close to its true color, early Neptune images had been "stretched and enhanced" to display its clouds, bands and winds, "and therefore made artificially too blue," study lead author Patrick Irwin, a planetary physicist at the Oxford University in the U.K., said in a statement.

"Even though the artificially-saturated color was known at the time amongst planetary scientists — and the images were released with captions explaining it — that distinction had become lost over time."

To resolve the misconception, Irwin and colleagues used new images from NASA's Hubble Space Telescope and European Space Agency's Very Large Telescope, whose instruments capture a rich spectrum of colors in each pixel, so processing them determined the "true apparent colors" of Uranus and Neptune. 

Then, the team revisited Voyager 2's images and rebalanced them in line with the new data, showing both planets are actually similar shades of blue. The color comes from a layer of methane in the planets' atmospheres, which absorbs red color from the sun's light.

Uranus is slightly whiter, the new study finds, possibly because its somewhat "stagnant, sluggish" atmosphere permits the methane haze to accumulate, which reflects red portions of sunlight to a greater extent than Neptune does.

The presence of amassed methane ice particles may also explain why Uranus changes its color slightly during its 84-year orbit around the sun. Images recorded between 1950 and 2016 by the Lowell Observatory in Arizona show the planet appears greener during its solstices — when one of its poles points toward the sun — and bluer during equinoxes, when the sun shines directly above its equator.

By comparing brightness of Uranus' poles to its equatorial regions in these images, Irwin and his team concluded methane is likely half as abundant near poles than at the equator, which accounts for the changing colors.

"The misperception of Neptune's color, as well as the unusual color changes of Uranus, have bedeviled us for decades," said Heidi Hammel of the Association of Universities for Research in Astronomy, who is not affiliated with the new study. "This comprehensive study should finally put both issues to rest."

This research is described in a paper published Thursday (Jan. 4) in the journal Monthly Notices of the Royal Astronomical Society.

When will we be able to see the planets at their best during this upcoming year of 2024?  Well, this guide will tell you. It will also provide information as to when a particular planet might be passing near to another planet, or a bright star for that matter, as well as the constellation that each will occupy during the course of the year. Read on to learn more about various circumstances like conjunctions, oppositions and elongations that are on this upcoming year's skywatching schedule. 

1. Mercury

As an evening star, Mercury appears in the western sky and sets about an hour after the sun does. As a morning star, it appears in the eastern sky, rising about an hour before the sun. There must be a clear, unobstructed horizon on these occasions. Mercury usually appears as a bright "star" with a yellowish or ochre hue. You can catch sight of the planet in the mornings of Jan. 5 to Jan. 26, May 2 to May 23, Aug. 30 to Sept. 19 and Dec. 18 to Dec. 31.  You can also catch some Mercury action in the evenings of March 10 to March 31, July 8 to July 29 and Nov. 2 to Nov. 23. 

Mercury will be brightest and easiest to spot in the evening sky between March 10 to March 31, and brightest and easiest to spot in the morning sky between Jan. 5 to Jan. 26 and again between Dec. 18 to Dec. 31.  

2. Venus

Always brilliant, and shining with a steady, silvery light, you can catch Venus during mornings in the eastern sky at dawn from Jan. 1 to April 8; evenings in the western sky at dusk from July 30 to Dec. 31.

The est time to view Venus in the morning sky in 2024 will come from Jan. 1 to Feb. 11. The best time to view Venus in the evening sky in 2024 will come from Oct. 5 through Dec. 31. On Feb. 22, Venus will be very close to Mars (passing 0.6-degree north of the Red Planet). Venus and Saturn will appear dramatically close to each other (Venus just 0.2-degree N) on the morning of March 21.

On April 3, Venus will slide just 0.3 degrees S of Neptune. On Aug. 5, Venus will pass 1.1-degree N of a bluish Regulus, the brightest star in the constellation of Leo, the Lion. On Nov. 22, Venus passes 1.1-degree N of Nunki, a second-magnitude star in the constellation Sagittarius.

3. Mars

This will be another "off" year for Mars, as for much of 2024 it will appear relatively dim while dawdling in the morning sky. Mars will actually be invisible for the first 10 days of the new year, too deeply immersed in the bright dawn twilight to be seen. On New Year's Day it will reside in the constellation of Sagittarius at a distance of 225.2 million miles (362.4 million kilometers) from the Earth. By April Fool's Day, it will be in the constellation of Aquarius and become visible low in the southeast for a few hours before sunrise, shining at magnitude +1.2. On July 1, it will be visible after midnight in the eastern sky, having brightened slightly to magnitude +1.0.

On Halloween, during late night hours, Mars will be readily seen in the northeast sky, with the "Twin Stars" of Gemini, Castor and Pollux, pointing directly at this yellow-orange planet, now shining at magnitude +0.1. 

From then on, through the balance of the year, Mars will rapidly ramp-up in brightness as it approaches the Earth. It will become stationary against the starry background of space on Dec. 6, performing a retrograde loop as a prelude to its first opposition since 2022 on Jan. 16, 2025. On New Year’s Eve, now in the constellation of Cancer, Mars will be 61.3 million miles (98.6 million km) from Earth and shine at magnitude -1.2, which is just a bit dimmer than Sirius, the brightest star in the night sky; this will be its brightest in 2024. 

Mars will pass 2.7 degrees north of the second magnitude star Nunki in the constellation Sagittarius on Jan. 21 and will get very close to Venus (passing 0.6 degrees south of that dazzling world) on February 22. Mars will make even closer approaches to Saturn (0.4-degree N) on April 10 and to Neptune (0.1-degree S) on April 29. The Red Planet will pass 4.9 degrees north of the similarly bright and orange tinted star Aldebaran on Aug. 4 and slide 0.3-degrees north of Jupiter on Aug. 14. 

Finally, early on the morning of Dec. 18, a waning gibbous moon will slide just above Mars. Across northern sections of North America, the moon will actually occult, or eclipse, the planet.      

4. Jupiter

Jupiter will be quite brilliant with a silver-white luster in 2024. It starts the year in the constellation Aries the Ram, then crosses over into Taurus the Bull on April 28 where it will remain for the balance of the year. 

During evenings from Jan. 1 to April 26, it'll shine brightly, as well as during mornings from June 8 to Dec. 6. Evening viewing will be optimal again from Decc. 7 to December 31.  

It's brightest in 2024 will fall between Nov. 14 to Dec. 28. Jupiter will be  in opposition to the sun on Dec. 7. It will pass 4.8-degrees north of the first magnitude star Aldebaran on July 9 and will be only 0.3-degrees south of a much-dimmer Mars on Aug. 14.

5. Saturn

Saturn shines like a yellowish-white "star" of moderate brightness. The famous rings, however, are only visible in a telescope. 

The rings were at their maximum tilt toward Earth in Oct. 2017, but are now rapidly closing to our line of sight. They will turn edge-on to the Earth during the spring of 2025. The process will begin in 2024 within the boundaries of the constellation Aquarius, the Water Carrier, and the planet will remain there for the rest of the year. 

You can catch Saturn during evenings from Jan. 1 to Feb. 11, mornings from March 17 to Sept. 7, then evenings again from Sept. 8 to Dec. 31. Saturn's brightest in 2024 will fall between Aug. 25 to Oct. 1. Saturn will be in opposition to the sun on Sept. 8. Saturn and Venus will appear dramatically close to each other (with Saturn just 0.2-degree S) on the morning of March 21 and will be 0.4-degree S of Mars on April 10.  

6. Uranus

Uranus can be glimpsed as a naked-eye object by people who are blessed with good eyesight and a clear, dark sky, as well as a forehand knowledge of exactly where to look for it. 

At its brightest, this planet shines at magnitude +5.6 and can be readily identified with good binoculars. A small telescope may reveal its tiny, greenish disk. Uranus spends all of 2024 in the constellation of Aries the Ram. You can catch sight of it during evenings from Jan. 1 to April 27, mornings from May 31 to Nov. 16, then evenings again from Nov. 17 to Dec. 31. It's brightest in 2024 will happen from Oct. 15 to Dec. 21. Uranus will arrive at opposition to the sun on Nov. 16.  

7. Neptune

Last but not least, Neptune will spends all of 2024 in the constellation of Pisces, the Fishes.  At a peak magnitude of +7.8, this bluish-hued world is only visible with good binoculars or a telescope. It'll be in the sky for optimal viewing during evenings from Jan. 1 through March 1, mornings from April 3 through Sept. 19, then evenings again from Sept. 20 to Dec. 31. 

It's brightest in 2024 will happen from July 23 to Nov. 19. Opposition is on Sept. 20. Two excellent opportunities to identify Neptune will come first on April 3, when Venus slips 0.3-degree S of Neptune, and again on April 29, when Mars passes a mere 0.1-degree S of Neptune. Keep in mind that, compared to Neptune, Mars will appear over 500 times brighter and Venus some 58,000 times more dazzling. 

On Christmas morning two years ago, astronomers and space fans received the gift they'd been waiting on for 30 years: the launch of the James Webb Space Telescope (JWST), the world's biggest, most daring endeavor to probe the earliest stars and galaxies in the universe. 

This year, the space observatory has continued to deliver breathtaking and scientifically valuable images of the cosmos. Here's a look back at the JWST discoveries that altered our understanding of the universe in 2023. 

1. The JWST takes a fresh look at our solar system

Although the JWST's purpose is to see some of the first stars and galaxies in the universe, its fresh look at our own solar system has been nothing short of breathtaking.

Take this image, which, in October, revealed a high-speed jet stream on Jupiter, previously unseen despite being over 3,000 miles (4,800 kilometers) wide and traveling at about 320 mph (515 km/h).

And back in June, the JWST identified carbon dioxide in the salty liquid oceans of Jupiter's icy moon Europa for the first time. The space observatory also offered a new look at Saturn in this image, which captures the gas giant's delicate ring system and three of its 146 known moons. The gas giant is eerily dark when seen through the JWST's infrared eyes, because in this wavelength, "methane gas absorbs almost all of the sunlight falling on the atmosphere," according to NASA.

The powerful observatory also captured this stunning image of Uranus, its brightest moons and 11 of its 13 known dusty rings.

Read more here: James Webb Space Telescope spots jet stream on Jupiter stronger than a Category 5 hurricane 

2. Nearby exoplanet has abundant life-supporting molecules

In September, the JWST discovered methane and carbon dioxide in the atmosphere of a fairly nearby exoplanet named K2-18 b, which circles a cool star 120 light-years from Earth and is larger than our planet but smaller than the giant planets in our solar system.

Previous observations with the Hubble Space Telescope had indicated that K2-18 b may be s a "Hycean world," an exoplanet that hosts thick, hydrogen-rich atmospheres with oceans of liquid water underneath. Recent observations with the JWST support that hypothesis, as the new data shows evidence for abundant methane and carbon dioxide but little ammonia.

"These results are the product of just two observations of K2-18 b, with many more on the way," study co-author Savvas Constantinou, an astronomer at the University of Cambridge, said in a statement. "This means our work here is but an early demonstration of what Webb can observe in habitable-zone exoplanets."

Read more here: Exoplanet's surface may be covered in oceans, James Webb Space Telescope finds

3. The JWST discovers its smallest object yet

In February, scientists were thrilled with the JWST's unexpected discovery of a small asteroid embedded in the main asteroid belt between Mars and Jupiter. Like most residents of that region, the space rock, which is about as tall as the Washington Monument, is thought to be a remnant of the formation of the solar system and thus contains tantalizing history about its evolution. 

Asteroids less than a mile long are difficult to spot with other telescopes, so the find underscored the telescope's usefulness closer to home.

Read more here: The James Webb Space Telescope just found an asteroid by total accident, its smallest object yet 

4. The JWST finds massive, mysterious galaxies in the infant universe

In February, scientists announced the discovery of galaxies as massive as the Milky Way sprinkled across the JWST's images of the universe just 500 million to 700 million years after the Big Bang. From what existing theories and models tell us, the galaxies the JWST found are too big, and the mature red stars in them too old, that the study authors said the find "creates problems for science."

"It calls the whole picture of early galaxy formation into question," study co-author Joel Leja, an astronomer at Penn State, said in a statement.

Read more here: The James Webb Space Telescope discovers enormous distant galaxies that should not exist 

5. An intensifying debate over the universe's expansion rate

We know that the universe is expanding at an ever-increasing rate, but we don't know precisely how fast. The issue has become a debate centered on resolving the correct value of the Hubble constant, an important number for estimating the universe's expansion rate. Right now, model estimates for the Hubble constant don't agree with values based on telescope observations.

This year, the JWST observed a class of stars known as Cepheid variables, which are usually humongous stars some 100,000 times brighter than the sun and the most reliable source to measure cosmic distances (and thus to tease out the universe's expansion rate). But instead of resolving the debate, the JWST's data only deepened the ongoing debate over the Hubble constant.

"I don't care what the value of the Hubble constant comes out to be," said Adam Riess, an astronomer at Johns Hopkins University and a Nobel laureate. "I want to understand why our best tools — our gold standard tools — are not agreeing with each other."

Read more here: James Webb Space Telescope deepens major debate over universe's expansion rate

6. Shining a spotlight on the first supermassive black holes

This year, the JWST helped astronomers see starlight from two early galaxies where they think one of the first supermassive black holes emerged. The JWST observed the galaxies as they were when the universe was younger than 1 billion years, showing how, over time, black holes gain unfathomable masses — often millions or billions of times that of the sun.

Read more here: James Webb Space Telescope sees 1st starlight from ancient quasars in groundbreaking discovery 

7. Complex organic molecules in a primordial galaxy

In June, astronomers revealed that the JWST had detected intriguing carbon-based molecules, similar to the ones found in oil and coal deposits on Earth, from over 12 billion years ago, when the universe was just 10% of its current age. In space, these molecules link to minuscule dust grains. Detecting them had been challenging because of the limits of our telescopes. However, "Webb really makes looking for organic molecules look too easy," Justin Spilker, an astronomer at Texas A&M University, told Space.com.

Read more here: James Webb Space Telescope spies earliest complex organic molecules in the universe

8. Yup, Maisie's galaxy is among the earliest ever spotted

This blurry orange blob, imaged by the JWST in summer 2022, is known as Maisie's galaxy, and in August 2023, astronomers announced that it's one of the earliest galaxies ever discovered. The galaxy seems to have existed when the universe was only 390 million years old, making it one of the four earliest galaxies ever seen. 

"This was the undiscovered frontier where we really didn't know how the galaxies formed or what they looked like until we went and looked for them with the JWST," study author Steven Finkelstein, an astronomer at the University of Texas at Austin, told Space.com. 

Read more here: James Webb Space Telescope confirms 'Maisie's galaxy' is one of the earliest ever seen 

9. The most distant supermassive black hole ever seen

In July, astronomers announced that the JWST had detected the most distant active supermassive black hole ever seen, whose host galaxy formed just 570 million years after the Big Bang. However, this ancient black hole has puzzlingly low mass —  just 9 million times that of the sun. For comparison, most of these cosmic beasts weigh over 1 billion solar masses. "It is still difficult to explain how it formed so soon after the universe began," the researchers said.

Read more here: James Webb Space Telescope detects most distant active supermassive black hole ever seen 

10. The JWST rediscovers an ancient ghostly galaxy

The JWST's sighting of a fuzzy galaxy embedded deep inside a dust cloud has been of recent interest to astronomers, in part because it is seen as it appeared just 900 million years after the Big Bang, when the very first stars were appearing. But astronomers are also interested in the science lessons this galaxy is waiting to reveal, "potentially telling us there's a whole population of galaxies that have been hiding from us," Jed McKinney, an astronomer at the University of Texas at Austin, said in a statement.

Read more here: James Webb Space Telescope pierces through dust to find an ancient ghostly galaxy 

11. The JWST spots 3 possible fabled "dark stars"

In July, astronomers reported that the JWST had found three bright objects that could possibly be "dark stars," a reference to the Grateful Dead song "Dark Star." The "stars" were originally tagged as galaxies by the JWST in 2022. 

"When we look at the James Webb data, there are two competing possibilities for these objects," Katherine Freese, a professor of physics at The University of Texas at Austin, said in a statement. "One is that they are galaxies containing millions of ordinary, population-III stars. The other is that they are dark stars. And believe it or not, one dark star has enough light to compete with an entire galaxy of stars."

Astronomers think these types of stars are powered by dark matter, the elusive substance that makes up 85% of the matter in our universe but is invisible to telescopes. If dark stars really do exist, their presence would help solve the puzzling observations of how a very young universe grew to host so many large galaxies as observed by the JWST, researchers say.

Read more here: Do fabled 'dark stars' actually exist? James Webb Space Telescope spots 3 candidates

12. The earliest galaxies looked surprisingly similar to our Milky Way

Galaxy evolution theories have predicted that the earliest galaxies in our universe were too young to flaunt any noticeable features, like spiral arms, bars or rings; astronomers have thought these more complex structures began appearing about 6 billion years after the Big Bang. But this year, the JWST found that galaxies with such delicate shapes could have existed as early as 3.7 billion years after the Big Bang. 

"Based on our results astronomers must rethink our understanding of the formation of the first galaxies and how galaxy evolution occurred over the past 10 billion years," study co-author Christopher Conselice, a professor of astronomy at the University of Manchester in the U.K., said in a statement. 

Read more here: James Webb Space Telescope reveals ancient galaxies were more structured than scientists thought

They may not be the gold rings from "The Twelve Days of Christmas," but Uranus and its rings stand resplendent in this stunning portrait from the James Webb Space Telescope (JWST).

It's the second image of Uranus that the JWST has captured this year. The first, released in April, was a two-toned affair composed of imagery captured at infrared wavelengths of 1.4 and 3.0 microns. This new image adds extra wavelengths, specifically 2.1 and 4.6 microns, to give a much more complete overview of the seventh planet from the sun. 

The new JWST Uranus image doesn't just show the planet, however. Uranus' aforementioned rings shine bright in infrared light, and the JWST's optics have even resolved the elusive, diffuse inner Zeta-ring. Many of Uranus' 27 moons are also on display; the cropped view shows some of Uranus' smaller, fainter moons including some embedded within the rings, while the wider view shows Uranus' five large moons: Ariel, Miranda, Oberon, Titania and Umbriel. 

Related: Rings around Uranus! James Webb Space Telescope captures stunning image of ice giant (photo, video)

The extra wealth of detail in these new images places Uranus' north polar cap in the spotlight. Unlike Earth and Mars' polar caps that are made from solid ice, Uranus is a gaseous world and its polar caps are hazy haloes of aerosols that hang high in its atmosphere. 

The JWST's new image shows Uranus' north polar cap almost directly facing us (and therefore also facing the sun), with a bright spot at its center and a dark collar, both of which have previously been seen in infrared and radio-wavelength observations, but never with this clarity before. The bright spot, seen as white in the new JWST, is warmer than its surroundings and is the center of a huge cyclonic vortex.

Bright storms are also visible blowing their way around the polar cap, and are believed to be at least partially caused by seasonal variations. Uranus is a really odd planet, in that for reasons unknown it rolls around the sun on its side, tilted by 98 degrees to the plane of the ecliptic (the plane of the orbits of the other planets). Rather than its poles being 'on top' of the planet, we see them head-on, and this brings with it unique climatic conditions that astronomers are eager to witness with the JWST in the run up to Uranus’ northern summer solstice in 2028.

It is at the solstice that the weather in the planet's polar cap becomes most active. Uranus' tilt means that for about a quarter of a Uranian year, which is 84 Earth-years long, one pole is in constant daylight and the other in enduring night. Right now the north pole is facing us, but in 2070 it will be the turn of Uranus' southern pole to bask in what passes for summer at such a great distance from the sun (2.96 billion kilometers/1.83 billion miles).

It seems strange now to think that back in 1986 when NASA's Voyager 2 mission flew past the ice giant, the general consensus was that blue–green Uranus appeared a bit boring, with a bland atmosphere that was a let down after the smorgasbord of atmospheric tumult seen on Jupiter and Saturn. Little did planetary scientists realize that at infrared wavelengths, which allow us to view beneath the featureless haze, Uranus has a lot going on, as the JWST's advanced vision shows.

Besides providing the best data yet for planetary scientists trying to figure out how Uranus’ atmosphere works, the observations will also prove vital in honing the scientific questions to be asked by a future mission to Uranus. 

The recent Planetary Science and Astrobiology Decadal Survey highlighted a mission to Uranus as its number one priority. Orbital alignments mean that a mission, which will take over a decade to reach Uranus, will need to launch by 2030; planetary scientists are still nervously awaiting the go-ahead from NASA. 

Until that time, we’ll just have to settle for the remarkable images that the JWST has to offer. 

When you're standing on Earth's surface, it's easy to forget that our planet is hurtling around the sun at more than 67,000 mph (107,800 km/h). And it's even easier to forget that there are seven other planets also making their way around our home star at similar breakneck speeds, or that all eight have been ceaselessly circling the solar system for billions of years. 

But what might really blow your mind is finding out how many trips around the sun each planet has under its belt. This may seem like a tricky thing to calculate, but because the planets' orbits have remained largely unaltered for most of their existence, all it takes is a bit of basic math.

Related: What's the maximum number of planets that could orbit the sun?

The solar system was born around 4.6 billion years ago, when the sun began to form from a cloud of dust left behind by prior stellar explosions. Around 4.59 billion years ago, the giant planets — Jupiter, Saturn, Uranus and Neptune — were born. And around 4.5 billion years ago, the smaller, rocky planets — Mercury, Venus, Earth and Mars — took shape, according to The Planetary Society.

But when the planets were born, their orbits around the sun were not the same as they are today (especially those of the giant planets). For around 100 million years after the first planets formed, there was a "dynamical instability" among them, which resulted in a gravitational tug-of-war between these large bodies and caused the rest of the outer solar system's planetary material, and even some emerging protoplanets, to be catapulted out of the solar system, Sean Raymond, an astronomer at the Bordeaux Astrophysics Laboratory in France and an expert on planetary systems, told Live Science in an email. 

However, once all of the planets had emerged and finished jostling with one another for their positions, they settled into consistent, stable orbits that haven't changed much since.

"For 98% to 99% of the solar system's lifetime, the planets' orbits have been nice and stable," Raymond said. As a result, you can use the planets' current orbital dynamics to make a pretty accurate guess at how many trips they have made around the sun, he added.

Take Earth, for example. Our planet takes a year to orbit the sun and has existed for 4.5 billion years, so it has taken roughly 4.5 billion trips around the solar system. 

However, the number of total orbits varies greatly among the other planets because their years are either shorter or longer than Earth's.

Mercury, the closest planet to the sun, takes only 88 days (or roughly 0.24 years, based on a year with 365.25 days) to travel around the sun once. So, over the past 4.5 billion years, it has completed around 18.7 billion solar orbits. But Neptune, the farthest planet from the sun, takes around 60,190 days (or 164.7 years) to complete an orbit, which means it has managed only about 27.9 million trips around the sun during its 4.59 billion years of existence. That means Mercury has orbited the sun around 18.7 billion times more than Neptune has.

Here is the full list of the planets, their year length and their total number of trips around the sun:

These sound like impressive numbers (and they are) but most of the planets could potentially double their number of orbits in their remaining lifetimes. 

In around 4.5 billion years, the sun will have swollen outward to reach Earth's orbit and transition into a red dwarf star, which will destroy Mercury, Venus and Earth. The other planets may live on for a time if they are not burned up but their orbits will likely be majorly altered.