2025 has seen stargazers look on in awe as a trio of magnificent comets barreled headlong into the inner solar system to survive a close brush with the sun, only to emerge to race back out into the blackness of space, never to be seen again.

Of these comets — the interstellar invader 3I/ATLAS, C/2025 A6 (Lemmon) and C/2025 R2 (SWAN) — not all survived their trial by solar radiation intact, while others drew the attention of a global audience thanks in part to their scientific significance and in some cases, the disinformation that swirled around them.

Join us as we look back at six of the most memorable cometary highlights of 2025, featuring stunning astrophotography, the unexpected advance of an interstellar invader and the dramatic demise of an icy visitor from the Oort Cloud.

5 incredible moments that made 2025 the year of the comet

1. Enter interstellar comet 3I/ATLAS

Comet 3I/ATLAS was discovered on July 1, 2025, by the NASA-funded ATLAS telescope in Rio Hurtado, Chile and was quickly confirmed to be just the third interstellar visitor to our solar system, after 1I'Oumuamua and 2I/Borisov.

Its exotic nature quickly seized the interest of the scientific community and the imagination of the public while simultaneously sending the conspiracy-peddling community into a frenzy, some of whom claimed that 3I/ATLAS was an alien spacecraft that had voyaged to the heliosphere for reasons unknown.

Follow-up observations confirmed 3I/ATLAS to be the brightest and potentially the largest interstellar object discovered to date, measuring up to 3.5 miles (5.6 kilometers) in diameter, based on observations from the Hubble Space Telescope, according to NASA.

2. When the cosmos gives you Lemmon, make astrophotography

If 3I/ATLAS was the most scientifically riveting of the cometary trio, C/2026 A6 (Lemmon) was arguably the most dynamic and photogenic. Comet Lemmon was discovered on Jan. 3 earlier this year and swiftly became a popular target among the astrophotography community, as it brightened from +21.5 to naked eye visibility around its close approach to the sun —known as perihelion — on Nov. 8.

Astrophotographers kept C/2026 A6 (Lemmon) firmly locked in their field of view throughout its journey, capturing each stage of its dramatic evolution. As it approached the sun, the increase in heat radiation caused icy matter in the comet's central nucleus to sublimate into gas, dragging dust particles with it.

The resulting cloud of cometary debris was then snatched up by the charged particles pouring out from the sun — called the solar wind — giving rise to a spectacular tail.

Astronomer Gianluca Masi captured a rare shot of the cosmic wanderer, when a glowing meteor tail in Earth's upper atmosphere appeared to wrap itself around Comet Lemmon's distant tail as it passed through the constellation Serpens on Oct. 24, creating a "a pure perspective miracle".

3. Comet SWAN dives through the Eagle Nebula

While Comet Lemmon's complex tail snagged the attention of astrophotographers worldwide, others took aim at the solar system wanderer C/2025 R2 (SWAN), which put on a magnificent show on Oct. 17, as it passed in front of the Eagle Nebula in the constellation Serpens.

Daniele Gasparri captured a striking view of C/2025 R2 (SWAN)'s vivid green coma as it hung in the pristine skies above the Atacama Desert in Chile, with the vast emission nebula serving as a jaw-dropping backdrop for the cometary body.

The pillars of creation, vast columns of interstellar dust and gas shaped by the radiation of nearby stars and made famous by the Hubble Space Telescope, can be seen nestled in the glowing heart of the vast nebula, to the left of the comet's glowing central nucleus.

4. Comet 3I/ATLAS reaches perihelion

Oct. 30 marked the climax of interstellar traveller 3I/ATLAS's headlong charge into the inner solar system, as it made its closest approach to the sun, passing 125 million miles (202 million km) from our parent star at the point of perihelion.

The event occurred just as 3I/ATLAS flew behind the sun from the perspective of Earth, robbing some of humanity's most powerful observatories of the chance to analyze the comet's chemical composition as it reached a peak of activity. Thankfully, perihelion was observed from elsewhere in the solar system by a flotilla of spacecraft orbiting Mars and travelling through interplanetary space.

3I/ATLAS finally emerged intact from behind the glare of the sun to become visible to Earthbound astronomers and skywatchers in early November, though it remained too dim to spot with the naked eye.

NASA subsequently held a press conference on Nov. 19 following the re-opening of the federal government, where it revealed several new images of the interstellar invader that documented its glowing central nucleus, sun-facing jet and growing tail. Conspiracy theorists were left somewhat broken-hearted by NASA Associate Administrator Amit Kshatriya, who noted, "It looks and behaves like a comet, and all evidence points to it being a comet", as opposed to the technologically advanced spaceship suggested by others.

5. K1 ATLAS breakup

One of the most dramatic cometary moments of 2025 occurred on the night of Nov. 11, when astronomers tracked the solar system comet C/2025 K1 (ATLAS) as its central nucleus broke into three massive pieces, following its close pass of the sun on Oct. 8.

The comet may have crumbled during its first visit to the inner solar system from the shell of icy material which surrounds its outer edge, known as the Oort Cloud.

The increase in heat radiation experienced during perihelion may have created a violent and sudden outflow of material from the nucleus, which could have undermined its structure, leading to the fracturing seen on Nov. 11, according to Elena Mazzotta Epifani of the Italian National Institute for Astrophysics.

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.

Comet C/2025 A6, better known as Comet Lemmon, was one of the latest icy visitors to swing through our neighborhood of the solar system, leaving astronomers and casual skywatchers equally delighted. For observers in Hawaii, the glow of the Milky Way didn't dim the streak of light made by this comet passing through.

What is it?

Comet Lemmon was discovered in January 2025 and made its closest approach to Earth in late October 2025. But by November 2025, when this image was taken, it had brightened to about the same apparent brightness as the planet Uranus, making it visible to the naked eye even from suburban skies.

Where is it?

This image was taken atop the volcanic peak Mauna Kea, on the Big Island of Hawaii.

Why is it amazing?

Comets are notoriously unpredictable, so Comet Lemmon's surprising visibility has felt like a bit of a cosmic bonus for Hawaiian stargazers. And this was a rare treat, as the comet won't return to Earth's skies for another 1,350 years, around the year 3375.

Framing this comet is the glow of our home galaxy, the Milky Way, which is easier to spot at higher elevations like Mauna Kea's peak, where there is less light pollution. The image gives us a souvenir from a celestial visitor that won't be back for more than a millennium.

Want to learn more?

You can learn more about comets and skywatching.

Astronauts orbiting Earth recently photographed not one but two comets while an aurora show danced below them.

The International Space Station (ISS) Expedition 73 crew took several pictures of comets Lemmon (C/2025 A6) and SWAN (C/2025 R2) in recent weeks that were just posted to NASA's website and social media pages after the end of the long government shutdown.

"Comets Lemmon and SWAN soar millions of miles away from Earth, beaming with auroras and airglow, in these celestial images from the orbital outpost captured in October," NASA officials wrote on the ISS X feed on Wednesday (Nov. 18).

Comets are small bodies made of ice and dust; when they approach our sun, radiation pressure and heat give them spectacular tails. Auroras are light shows that happen when charged particles from the sun interact with Earth's atmosphere and magnetic field, while airglow is luminescence caused by chemical reactions high in the atmosphere.

NASA didn't say who on the crew took the photos, but they look very similar to images taken by Japan Aerospace Exploration Agency (JAXA) astronaut Kimiya Yui. Yui, unlike the NASA crew, was able to keep posting on social media channel X during the shutdown. (The NASA astronauts were allowed to perform only essential duties during the shutdown, such as ISS science and maintenance.)

Yui provided descriptions of his photos as well. "You can … distinguish between the two types of tails: ion and dust," Yui wrote (in Japanese; translation by xAI's Grok tool) on Oct. 20 of a Lemmon image with the comet backdropped by a starry, bluish-purple sky. (NASA posted a similar image from that same day on its website.)

More images came quickly. "After a busy day comes to an end, I've been continuing to take photos to soothe my fatigue. Lately, my source of healing has been Lemmon-chan, I suppose?" Yui posted on X with a series of images on Oct. 22. "I find myself thinking things like, 'What kind of expression will you show me today, I wonder?' and heading toward the window, and that moment feels as enjoyable as heading out on a date."

Yui sent out another image series on Oct. 21, noting changes in Lemmon's brightness and tail — as well as changes in Earth's atmosphere. Both the Oct. 21 and Oct. 22 photo sets on Yui's feed are similar to an Oct. 23 image on NASA's website.

Then, on Oct. 24, Yui found Lemmon appearing to melt into a spectacular aurora of green and yellow light, which looks like an entry on NASA's image website. Lemmon was 57.2 million miles (92.1 million kilometers) from Earth and the ISS was above Fargo, North Dakota when the image was taken.

"It was just like a mermaid swimming through a sea of auroras," Yui said of Lemmon. He added the show was "too magnificent" to use the familiar "chan" honorific when referring to Lemmon, so he chose to adopt the more formal "Lemmon-san."

That same day, Yui pivoted his attention to what NASA identifies as Comet SWAN, which was about 27.2 million miles (43.8 million km) from Earth at the time. "As the comet approaches the sun, the opportunities to photograph it from the ISS have become very short," Yui noted of the image, which shows SWAN floating above green and yellow bands of airglow off the coast of Newfoundland and Labrador, Canada.

It's rare to have two bright comets visible in the sky at roughly the same time, and especially rare for them to peak in brightness so close to each other: Lemmon and SWAN both were at their brightest around Oct. 20 and Oct. 21.

Lemmon was discovered in January by University of Arizona astronomer David Carson Fuls in images from the Mount Lemmon Survey, using the university's eponymous telescope near Tucson. SWAN was found in September by Ukrainian amateur astronomer Vladimir Bezugly using images from the Solar Wind Anisotropies (SWAN) instrument on the European Space Agency's space-based Solar and Heliospheric Observatory (SOHO).

For skywatchers, scientists and even the astronauts on the International Space Station (ISS), the skies have recently been very active. The sun has released its largest eruptions of 2025, sparking a series of auroras that, in the Northern Hemisphere, have reached as far south as Mexico.

Add to this two comets that have been seen in the night sky, comet Swan and comet Lemmon. While the astronauts on the ISS had to take shelter during the recent solar storms to avoid potentially dangerous radiation, they did manage to capture this image of comet Lemmon appearing near the auroras on Earth.

What is it?

Comet Lemmon, officially designated C/2012 F6 (Lemmon), is a long-period comet discovered in 2012 by the Mount Lemmon Survey in Arizona. It originates from the distant Oort Cloud, the icy reservoir of cometary bodies that surrounds our solar system.

As it approaches the sun during its 1,350-year orbit, comet Lemmon warms, releasing gas and dust that form its signature glowing tail.

Where is it?

This image was taken in low Earth orbit aboard the International Space Station, which circles our planet at an average altitude of about 250 miles (400 kilometers).

Why is it amazing?

Because of their long orbits, comets are a relatively rare sight in the night sky. And catching one juxtaposed against powerful auroras is rarer still.

This photo is a good reminder of how dynamic, multi-layered and interconnected our corner of the universe really is, and how once in a while, things line up just right to capture something truly extraordinary.

Want to learn more?

You can learn more about comet Lemmon and space weather.

Recent months have seen space fans revel in a wealth of spectacular astrophotography depicting the evolution of Comet Lemmon's glowing coma and twisting tail as it journeyed through a Northern Hemisphere night sky swarming with satellites.

While the vast majority of photographers opted to post sanitized views of Comet Lemmon, others intentionally compiled their images to reveal the incredible number of satellites that crossed the night sky over the course of multiple exposures.

In each instance, Comet Lemmon is shown surrounded by a crazed network of thin, web-like lines, each of which represents the path of an orbiting satellite over the course of a short camera exposure.

"Photographically, if someone is attempting to take a single image of a target and needs the image to be 'clean' — free of manmade objects — well, that image is nearly impossible to obtain," astrophotographer Dan Bartlett told Space.com in an email. "Every single subframe I take (prior to stacking) now contains at least one, and usually more than one satellite streak."

There are currently about 13,000 operational satellites orbiting Earth, of which about 8,900 are SpaceX Starlink craft. This number is set to exponentially increase, with SpaceX alone aiming to orbit up to 42,000 of its internet-beaming spacecraft, while competing companies aim to add thousands more satellites to their own "megaconstellations."

Thankfully, astrophotographers have access to powerful editing tools that allow them to remove the unsightly streaks with ease.

"Despite the enormous increase in satellite traffic over the past few years, eliminating the satellite trails in post processing is actually fairly simple using the right tools," explained Bartlett. "I certainly don't like seeing so many satellites everywhere I point my telescope or even a good pair of binoculars, but we're still not at the point where you can't enjoy the night sky (there can be a thrill seen visually when a satellite passes through your field of view)."

Astrophotographers combat satellite streaks by capturing a multitude of short exposures over the course of a single session. The images are then combined and subjected to an algorithm that determines a median value for each pixel before rejecting outlier pixels with values that exceed set parameters.

"If you take at least a dozen images to stack, then you can use a combine method called Sigma Rejection," said astrophotographer Chris Schur in an email to Space.com. "This is available in nearly all astronomical imaging processing software. A single shot to up to about 6 images, the sigma does not have enough data to reject all the trails. So that's why comet and deep-sky imagers take sets of at least a dozen images as a normal process, so that the stacking software has a good set to perform its algorithm."

The end result is a gorgeous composite image of an ancient solar system comet, which has been locked in an orbital dance around the sun since the creation of the planets over four billion years ago.

Stargazers looking to capture their own views of the night sky should check out our picks for the best cameras and lenses for astrophotography, along with our guide to observing and photographing comets.

Editor's Note: If you would like to share your comet astrophotography with Space.com's readers, then please send your photo(s), along with your comments, name and the times and dates of your shoot to spacephotos@space.com.

Comets of this type aren't everyday sightings. The opportunity to observe objects that might have orbital periods measured in thousands of years is fleeting. So when Comet Lemmon recently appeared in the night sky, eager skywatchers looked up to observe it move across the heavens.

What is it?

Comet Lemmon, or C/2025 A6, was discovered by the Arizona-based Mount Lemmon Survey, which observed it as an almost asteroid‐like object; it was later re-classified as a comet once coma and tail features became evident.

Comets are often described as "dirty snowballs" — icy bodies laced with dust and rock — from the fringes of the solar system. When they approach the sun, they heat up, releasing gas and dust that form the coma (the glowing cloud around the nucleus) and the tail(s) that stream away from them. Studying these phenomena gives insight into primordial solar system material.

In recent years, improved survey telescopes (like those used in the Mount Lemmon Survey) and more frequent astrophotography mean we're discovering and documenting more comets than ever. Yet, large and bright comets visible even to the unaided eye remain uncommon.

Where is it?

This photograph was taken near Pedraforca mountain in the Bergueda region in Spain.

Why is it amazing?

The image provides more than just a beautiful view; it records a moment of active sublimation: dust and gas escaping the nucleus due to solar heating. The color of a comet's coma often indicates what gases may be fluorescing under solar UV radiation, offering clues to the icy body's composition. Capturing the tail and coma structure helps astronomers model the dust production rate, tail shape and size, and how the comet is interacting with the solar wind and radiation pressure.

Want to learn more?

You can learn more about astrophotography and Comet Lemmon.

Halloween is upon us and the 2025 spooky season is abuzz with talk of three cosmic visitors — Comet Lemmon, Comet SWAN and the interstellar traveler 3I ATLAS — said to be haunting the night sky. But when it comes to stargazing, one of these ghostly wanderers is more trick than treat!

Comets are composed of primordial matter left over from the creation of our solar system — and others — which become active as they approach the sun, as the increase in heat radiation causes icy materials to transform into a gaseous shell around the nucleus. That shell is then blown away by the solar wind — the relentless stream of charged particles issuing forth from our star — creating a tail that reflects sunlight..

Read on to discover how to find Comet Lemmon, SWAN and the interstellar visitor 3I ATLAS in the Halloween night sky. If you're mew to stargazing check out our guide to the best smartphone astronomy apps to help you find your way amongst the sea of stars.

A Cometary trick, or a stargazing treat?

Comet Lemmon — A Halloween treat

Comet C/2025 A6 Lemmon has brightened dramatically over the past month. It currently boasts a magnitude — or apparent brightness — of around +4.2, according to the Comet Observation Database, which would render it visible as a hazy patch of light from a dark sky location.

Whilst it's possible to view Comet Lemmon with the naked eye, a pair of 10X50 binoculars or even a modest backyard telescope will help reveal the sunlight reflecting from the icy wanderer's central coma and magnificent, elongated tail.

Comet Lemmon will be positioned low on the western horizon, embedded among the stars of the constellation Ophiuchus in the hours following sunset on Oct. 31. After locating the constellation, use your smartphone astronomy app to pinpoint the stars Kappa Ophiuchi and Epsilon Ophiuchi. Comet Lemmon will shine roughly halfway between these two stellar giants, near the magnitude +3.8 star Marfik.

Interstellar Comet 3I/ATLAS — a skywatching trick

Comet 3I/ATLAS has been haunting the news cycle ever since its discovery in July 2025, when it was swiftly confirmed to be the third interstellar visitor ever to visit our solar system after being created in the orbit of a distant star. Its surprise appearance garnered significant attention from the public, conspiracy theorists and the scientific community alike, the latter of which is actively observing the object with a host of ground-based observatories and spacecraft to gather as much data as possible before it races out of view.

3I/ATLAS made its closest approach to the sun — an event known as perihelion — on Oct. 30 and has a current approximate magnitude of just +11, placing it well below the light detection threshold of the unaided human eye. Sadly, the interstellar visitor is still very close to the sun and so won't make for a good telescopic target on Oct. 31.

On Halloween night, 3I/ATLAS will be positioned close to the rocky planet Venus in the constellation Virgo, which will rise highest in the hour preceding dawn on Nov. 1, bathed in the glow of the rising sun. The cosmic interloper is expected to emerge from behind the glare of our parent star by early December, according to NASA, though its apparent brightness will likely have dipped significantly by then, as it passes ever further from the sun's radiation, on an escape trajectory from our solar system.

Comet C/2025 R2 (SWAN) — A telescopic challenge

Comet SWAN was discovered on Sept. 10 by Ukrainian amateur astronomer Vladimir Bezguly and quickly became a popular target for the astrophotography community, who succeeded in capturing incredible detail in the icy wanderer's majestic tail.

SWAN's brightness is currently on the decline following its close brush with Earth on Oct. 21. Its estimated magnitude of 7.2 renders it too dim to be spotted with the naked eye, though a pair of 10X50 binoculars or a small backyard telescope will help reveal the hazy reflected light centered around its icy nucleus shining against the blackness of space. However, the light of the 76%-lit moon will present an added challenge to spotting the comet on the night of Oct. 31

Look to the southern horizon in the hours following sunset on Halloween to find the moon glowing among the stars of the constellation Aquarius. Next, locate the bright magnitude 3 stars Sadalmelik and Sadalsuud, which form the shoulders of the "water bearer" depicted in the stellar formation. Comet SWAN can be found in the patch of sky two-thirds of the way from Sadalsuud to Sadalmelik.

Comet SWAN is now rushing headlong away from the sun on a highly eccentric orbit that takes it well beyond the orbit of icy Neptune, and it isn't expected to return for another 1,400 years after it disappears from Earth's skies, so catch it while you can!

Stargazers interested in creating a lasting view of the transient visitors to Earth's sky should check out our guide to observing and photographing comets, along with our roundups of the best cameras and lenses for astrophotography in 2025.

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

Astronomer Gianluca Masi captured spectacular footage of a glowing meteor trail wrapping around the colossal tail of Comet Lemmon on Oct. 24, as the wandering solar system body approached the constellation Serpens Caput in Earth's sky.

The bright meteor tore through the night shortly before Masi snapped a two-minute exposure of Comet Lemmon with an astrographic camera operated by the Virtual Telescope Project in Manciano, Italy at 1:43 p.m. EDT (1743 GMT) on Oct. 24.

Masi's image caught the stream of ionized gas left in the meteor's wake as it rapidly expanded and rose in the upper atmosphere to create a visually spectacular wave effect, which appeared to wrap around Comet Lemmon's tail from our Earthly perspective. A subtle fan-like pattern can also be seen rippling across the image, created as wayward light struck the camera sensor.

"The phenomenon is associated with the ionization of molecular oxygen in the atmosphere caused by the meteor event, followed by its recombination, which produces the emission of light at that wavelength," Masi wrote on the Virtual Telescope Project's website.

Under certain conditions, these glowing trails can appear to form spirals in the upper atmosphere. But despite how intertwined the two appear in the photo, Masi writes, the coiling afterglow of the meteor is actually quite far from the tail of Comet Lemmon. "In this photograph, the meteor's afterglow appears to coil around the comet's ion tail — a pure perspective miracle, since the former is an atmospheric effect induced by the meteor, while the comet itself was about 100 million kilometers away."

Masi also released a spectacular timelapse of the event captured between 1:37 p.m. (17:37 GMT) to 2:12 p.m. (18:12 GMT) on Oct. 24 showing the meteor's ion trail twisting around Comet Lemmon as satellites left streaking trails through the image frames.

Comet Lemmon has brightened dramatically since its discovery in January earlier this year and is currently estimated to have a magnitude of approximately +4.2, according to the Comet Observation database (COBS) run by the Crni Vrh Observatory in Slovenia. Magnitude is the scale used to measure the apparent brightness of objects in the night sky. The lower the number, the brighter the object. That means that it's possible to spot the comet as a dim, hazy patch of light under dark sky conditions, though a pair of 10X50 binoculars or a backyard telescope will help resolve its light!

In late October, Comet Lemmon can be found travelling away from the constellation Serpens Caput towards the constellation Ophiuchus, the serpent-bearer, ahead of its close approach to the sun on Nov. 8.

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

Comet Lemmon will cut through the neck of a cosmic serpent on the night of Oct. 26, when it passes through the stars of the constellation Serpens Caput ahead of its close approach to the sun in early November.

The wandering comet Comet C/2025 A6 (Lemmon) was discovered on Jan. 3 earlier this year and has been brightening dramatically over the course of its subsequent headlong dive into the inner solar system. The brightening occurred as an increase in heat radiation from the sun vaporized icy materials embedded in its structure, creating a gaseous shell around its nucleus. The cometary material was then caught up in the solar wind, leading to the formation of a visually spectacular tail that shines in the reflected light of the sun.

Comet Lemmon is currently estimated to have a magnitude of around +4.3 according to the Comet Observation Database (COBS) run by the Crni Vrh Observatory in Slovenia, which should make it visible to the unaided eye from dark sky locations.

Look to the western horizon from a dark sky location at sunset on Oct. 26 to find Comet Lemmon's hazy light shine directly beneath the triangle formation of stars representing the head of the great snake in the constellation Serpens Caput. By the following night, the comet will have cut through the neck of the celestial serpent to approach the constellation Ophiuchus, the "snake bearer".

Serpens is the only constellation that appears in two halves in the night sky, with Serpens Caput appearing to the right of the constellation Ophiuchus, with Serpens Cauda — the tail — appearing to the snake bearer's left.

Whilst Comet Lemmon is technically bright enough to view with the naked eye from a dark location, a telescope or binoculars will help reveal the reflected light of the ancient visitor. Be sure to check out our guide to photographing and observing comets and to peruse our roundups of the best cameras and lenses for capturing the night sky if you're looking to update your gear!

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

Update for Oct. 21: Due to cloudy weather, this livestream was rescheduled for Oct. 24, beginning at 1:30 p.m. EDT (1730 GMT).

Two comets, C/2025 A4 (Lemmon) and C/2025 R2 (SWAN), are about to reach their closest approach to Earth and you can watch the action unfold live online.

Astronomer Gianluca Masi and his Virtual Telescope Project will host a special livestream on Oct. 24 beginning at 1:30 p.m. EDT (1730 GMT) to watch as both comets make a close pass to Earth, making them well placed for observations.

"So far, living in the Northern hemisphere, I could admire C/2025 A6 Lemmon only,
but C/2025 R2 SWAN is quickly joining the show and we are ready to amaze every
astronomy lover with our live feed!" Masi told Space.com in an email.

You can watch the cosmic show live here on Space.com courtesy of the Virtual Telescope Project or on the project's website or YouTube channel, weather permitting.

Rare double-comet encounter

Having two right comets visible in the sky around the same time is a rare cosmic treat. During the event, Comet Lemmon (C/2025 A6) will pass about 56 million miles (90 million kilometers) from Earth, while Comet Swan (C/2025 R2) will soar even closer, at roughly 24 million miles (39 million km). Both are expected to peak in brightness between Oct. 20 and Oct. 21.

Comet C/2025 A6 (Lemmon) was discovered in January 2025 and has been steadily brightening as it soars through the inner solar system. Lemmon is visible in a pair of binoculars or small telescopes in the western evening sky after sunset, slowly climbing higher each night as it moves northward.

Comet C/2025 R2 (SWAN) was discovered in September 2025 by the Solar and Heliospheric Observatory's SWAN instrument. It is best viewed in the predawn sky, when the comet appears low on the eastern horizon as it continues its journey away from the sun.

If you're hoping to spot the comets yourself, check out our guides to the best binoculars and best telescopes for beginners, as well as our how to photograph comets guide. And don't forget to explore our night sky guide for more celestial highlights this month.

Editor's note: If you capture a photo of Comet Lemmon or Comet SWAN and would like to share it with Space.com, send your images and comments to spacephotos@space.com.

Award-winning astrophotographer Josh Dury has captured a stunning view of Comet C/2025 A6 (Lemmon) shining in the sky over Somerset in the U.K. ahead of its close approach to Earth on Oct. 21.

Dury revealed Comet Lemmon's bright green coma and long diffuse tail streaking through the eventing sky in exquisite detail as day gave way to night above the Mendip Hills area Oct. 12.

Comet Lemmon's tail was formed when heat radiating from the sun caused icy materials embedded in its ancient body to transform directly into gas, a process known as sublimation. This diffuse cloud of debris was then blown away by the steady stream of charged particles emanating from our sun known as the solar wind — hence why a comet's tail is always seen pointing away from the sun.

Dury worked through haze and high wind to capture a breathtaking shot of the distant night sky visitor using his Sony A7S III camera in concert with a Sigma 135mm F/1.4 Art lens, as a diffuse pink aurora glowed close to the horizon. "I would say in this instance, the weather was more the challenge," Dury told Space.com. "With anti-cyclonic gloom affecting the weather for the best part of a week or more, there wasn’t much opportunity to photograph the comet from here in the West Country. Taken from higher ground, I was surrounded by haze, mist and fog."

Comet Lemmon has a current magnitude of around +4.9, which should make it visible to the naked eye from dark sky locations. The comet is expected to continue to brighten ahead of its close approach to Earth, after which it will gradually fade from our skies for over a thousand years. During that time, it will undertake an elliptical tour of the distant solar system that will take it well beyond the orbit of the gas giant Neptune.

Stargazers hoping to capture an image of Comet Lemmon before it disappears from Earth's sky should consider picking up a copy of Dury's book 52 Assignments: Night Photography, which gives tips on how to image comets and countless other deep sky targets. Be sure to also check out our finders guide detailing where and when to look for Comet Lemmon throughout October.

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.

Astrophotographer Brennan Gilmore has captured spectacular views of the solar wind stripping a vast section from C/2025 A6 (Lemmon)'s tail, as the icy wanderer continues to brighten ahead of its close approach to Earth on Oct. 21.

Comet Lemmon has brightened dramatically since its discovery on Jan. 3,, raising hopes that it could become a spectacular naked eye comet in October as it nears the closest point to the sun in its 1,350-year orbit on Nov. 8 — a point known as perihelion.

Gilmore's image gives us a spectacular view of Comet Lemmon's glowing green coma as it passed close to the bright star TW Leonis Minoris in the constellation Leo Minor on Oct. 4. A long luminous tail stretches away from the comet's nucleus, as material ejected from the comet reflects the light of the nearby sun.

A comet's tail is constantly being blown by the steady stream of charged particles emanating from the sun collectively as the "solar wind". As such, it will always point away from the sun, rather than simply trailing a comet's direction of travel, like the exhaust trail of an aircraft.

Gilmore released a stunning 60-minute timelapse of Comet Lemmon as a colossal section of its tail was buffeted and stripped away by the solar wind on Oct. 2, during a spectacular disconnection event. The images were taken using a Takahashi Epsilon 130D Newtonian telescope in conjunction with a ZWO astronomy camera from Cismont, Virginia.

Comet Lemmon continues to brighten, with some observations posted by the Comet Observation Database (COBS) run by the Crni Vrh Observatory in Slovenia, putting its brightness at +5.1, which would make it detectable as an extremely dim object to the unaided eye from a dark sky location.

Be sure to check out our finder's guide if you're hoping to lay eyes on Comet Lemmon as it brightens further in October and read our tips on how to photograph a comet if you want to create a permanent memory of the wandering body before it disappears from our skies,

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.

Autumn has draped itself across the northern hemisphere, heralding the onset of longer, darker nights that serve as the perfect backdrop for amateur astronomers looking to explore the wonders of the night sky.

Our sky is constantly changing as the relentless passing of the seasons and movement of the planets, moon, comets and Earth itself bring an ever-shifting array of astronomical targets into view.

Join us as we explore a selection of spectacular sights picked to highlight the diversity of the autumn sky, which will be visible both through telescopes and binoculars, or even the naked eye, assuming one particular comet continues its brightening trend!

8 skywatching targets to look out for this autumn

Orion, the hunter

The constellation Orion rises in the east around midnight in mid-October and makes for a spectacular sight in the predawn sky, by which time the stellar formation will have drifted to a position high above the southern horizon.

Orion's Belt

Look for the three stars that make up the distinctive formation of Orion's Belt — Alnitak, Alnilam and Mintaka — shining roughly 40 degrees above the southern horizon before sunrise. To estimate 10 degrees in the sky, use the width of your clenched first held at arm's length.

Betelgeuse

Above Orion's Belt, the red giant Betelgeuse marks the hunter's right shoulder in constellation drawings, though it appears on the left when viewed in the sky. Betelgeuse, formally known as Alpha Orionis, will one day end its life in a spectacular supernova explosion upon exhausting the last of its fuel, which could be as bright as the full moon.

Orion Nebula

Those viewing from a dark sky location may also notice a blurry patch of light hanging about 5 degrees below Orion's belt. That smudge is the Orion Nebula, which at a distance of just 1,500 light-years is one of the closest star-forming regions to Earth and makes for a beautiful target through binoculars or a 6-inch telescope.

The Orionid meteor shower

The Orionid meteor shower is active from Oct. 2 to Nov. 7 and reaches a peak of activity on Oct. 20-21, when up to 20 shooting stars may be seen streaking through the night sky each hour.

Orionid meteors appear to emanate from a point in the sky known as a radiant located close to the red giant Betelgeuse. To find meteors with the longest trails, it's best to allow up to 30 minutes for your eyes to adjust to the dark and find a point 40 degrees above the radiant, where the meteor trails will be at their longest.

The shower is best viewed in the hours between midnight and dawn on Oct. 21 and unfolds against a stunningly dark, moonless sky.

The Andromeda Galaxy

The Andromeda Galaxy lies almost directly overhead in the hours surrounding midnight on October nights, presenting a perfect opportunity to observe the Milky Way's closest neighbor without the atmospheric interference that comes from being close to the horizon.

Andromeda is a vast spiral galaxy formed from the merging of multiple smaller galaxies billions of years ago. The vast cosmic structure spans about 260,000 light-years and contains over a trillion stars.

The galaxy is bright enough to be spotted by the naked eye in dark sky conditions as a faint oval-shaped blur in the night sky, while a telescope with an aperture of around 6-inches will help reveal its bright core surrounded by a haze of light.

To find Andromeda, locate the constellation Cassiopeia, which forms a prominent 'M' shape high in the northern sky. The left three stars of the 5 star formation will form a pointer, with Alpha Cassiopeiae, or Shedar as its tip, guiding you to our galactic neighbor.

Comet C/2025 A6 (Lemmon)

Now to the wildcard on our list. Comet C/2025 A6 (Lemmon), discovered on Jan. 3 by astronomers using a 60-inch telescope located in the Mt. Lemmon Observatory in Arizona. The wandering comet has brightened significantly as it has drawn closer to the sun throughout the year, prompting an increase in activity as masses of dust and gas are shed by the wandering body and subsequently illuminated by sunlight.

Comet Lemmon's bright nucleus and ethereal tail are already visible as a hazy patch of light through backyard telescopes and astronomy binoculars, while many are excited by it brightening enough to become a naked eye target in the coming weeks!

Lemmon is constantly shifting against the background stars beyond and is best viewed in the hours preceding dawn for those in the northern hemisphere. It can be found in mid-October, passing close to the bright star Psi Ursae Majoris in the constellation Ursa Major, moving towards the brightest stellar body in the constellation Canes Venatici, known as Cor Caroli.

Check out our guide on how to view and photograph comets if you're interested in capturing your own image of Comet C/2025 A6 Lemmon before it disappears from Earth's sky for over a thousand years.

The gas giant Saturn

Saturn makes for a particularly bright and magnificent target in the Autumn months, having recently reached opposition — the point at which it is opposite the sun in our sky — just a few weeks ago.

The gas giant will appear as a bright "evening star" shining above the eastern horizon at sunset in October, below the head of the great Western Fish represented in the constellation

A telescope with an aperture of 6 inches or more will allow you to resolve the cloud bands dividing its majestic disk, along with the razor-thin profile of its sweeping rings, which are currently oriented almost edge-on to Earth, following its ring plane crossing in March earlier this year. It may be beneficial to fit color filters to your telescope to help reveal subtle details in Saturn's cloud surface, according to telescope maker Celestron.

If you're looking to upgrade your equipment, check out our guides to the best telescopes and binoculars for viewing the night sky as we move towards peak astronomy season. Our guides on the best cameras and lenses for imaging the night sky can help to ensure that you're ready to make the most of the next big skywatching event.

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.

The past month has seen Comet C/2025 A6 (Lemmon) brightening rapidly ahead of its close approach to the sun, leading to growing excitement that it could shine brightly enough to be seen by the naked eye in mid-late October.

Solar system comets tend to become increasingly active and bright in the weeks and months leading up to perihelion — their closest approach to the sun in a given orbit — and Comet Lemmon is no exception. Heat and energy from the sun vaporizes the comet's icy deposits, transforming them into a gaseous central coma and tail that drags dusty particles along with it, which reflect sunlight and create the dramatic spectacles we see through telescopes or in the night sky.

Read on to discover where and when to look for Comet Lemmon before, during and after its flyby of Earth on Oct. 21.

Comet Lemmon has brightened from magnitude +21.5 upon its discovery in January to approximately +5.7, according to the Comet Observation Database (COBS) maintained by the Crni Vrh Observatory in Slovenia. That technically places it above the +6 detection limit of the human eye in perfect dark sky conditions, though the light cast by the waning gibbous moon will add an extra barrier to visibility in the week ahead.

If Comet Lemmon continues its current brightening trend, it could become a beautiful, hazy naked eye target in the coming weeks, with its light becoming easier to define through a pair of binoculars, or a backyard telescope.

Much like the planets and the moon, Comet Lemmon is constantly shifting relative to the stars beyond. Mid-October will see the wandering body pass close to the star Alkaphrah, or Chi Ursae Majoris in the constellation Ursa Major, just below the 'dipper' portion of the Big Dipper asterism, before beating a path through the night sky towards the star Cor Caroli in the constellation Canes Venatici.

Comet Lemmon will be in the heart of the constellation Boötes, the Herdsman, as it makes its closest approach to Earth on Oct. 21, before travelling on to pass beneath the head of the great serpent represented in the constellation Serpens on Oct. 26 to 27.

The optimal hour to search for the comet will shift depending on the time of the month in which you are looking. Comet Lemmon will be positioned high above the northeastern horizon in the hours preceding dawn in early October, but will have transitioned to the evening sky by the time it makes its close approach to Earth on Oct. 21, when it will appear low on the northwestern horizon.

Interested in capturing Comet Lemmon with a camera for yourself? Then be sure to read our guide on how to image a comet, along with our picks of the best cameras and lenses available for astrophotography in 2025. Amateur astronomers should also check out our roundups of the best telescopes and binoculars for viewing the night sky.

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.

Comet Lemmon (C/2025 A6) is quickly brightening as it draws closer to both the sun and Earth, evolving into a striking object already visible through small telescopes and binoculars and soon, quite possibly, to the naked eye.

The icy visitor, discovered on Jan. 3 by the Mount Lemmon Survey in Arizona, is the brightest comet to appear in our sky since Comet C/2024 G3 (ATLAS) last January. It will swing close to the sun, a point called perihelion, on Nov. 8, passing about 49.25 million miles (79.25 million kilometers) from our star.

Now, as it brightens rapidly in the predawn sky, skywatchers around the world are preparing for its best and possibly brightest display in late October.

What to expect

Typically, during a given year, several comets will appear that come within range of good binoculars or small telescopes. But a comet bright enough to be readily visible to the unaided eye comes along usually only once or twice per decade.

According to the most optimistic forecasts, at its brightest later this month, comet Lemmon is projected to possibly approach +3 magnitude (such a brightness is comparable to the star Megrez, the star in the Big Dipper that joins the handle with the bowl). So, these upcoming weeks will afford skywatchers an unusual opportunity.

Of course, a comet's appearance is much different and less well defined than the sharp image provided by a star. In August 1974, Kenneth Weaver, an assistant editor of National Geographic magazine, provided an excellent description of a comet somewhat comparable to Lemmon. Weaver had traveled to the dark skies of Kitt Peak National Observatory near Tucson, Arizona, for a glimpse of Comet Kohoutek. He wrote:

"No spectacular lighting of the sky, no radiant display; One moment it was not there, the next moment it appeared. To the naked eye, it seemed as though a giant paintbrush, dipped in whitewash, had been drawn swiftly across the black wall of heaven, leaving a ghostly swath above a gently glowing blob."

But when Mr. Weaver wrote these words more than half a century ago, he was describing a modestly bright comet from a location completely free of light pollution. Today, with the glare of bright lights seemingly metastasizing everywhere, it is far more difficult to find such dark, starry and pristine conditions. Urban skyglow has robbed many of us of our night skies and the vast majority of the population of the United States now lives in regions where the stars are mostly blotted out by excessive lighting.

If you live in a bright city or suburban area, your best chance to see Comet Lemmon will be to head to a dark-sky site far from streetlights. Look for a place where the Milky Way is visible overhead — a sign of truly dark conditions. Under hazy, light-polluted skies, the comet may appear faint or not at all.

Related: Astrophotographers capture dazzling new views of Comet C/2025 A6 (Lemmon) as it brightens for October skies

Comet metamorphosis

Comet Lemmon has proven to be a particularly active comet, with noticeable changes occurring almost from night to night. As it races toward the inner solar system, the comet will continue to brighten through October while gradually expanding in size.

Its closest approach to Earth (perigee) comes on Oct. 21, when it will pass about 55.4 million miles (89.2 million km) from our planet.

Predicting what a comet will look like, however, is notoriously tricky. Its brightness, color, and tail shape depend on several factors: its orbit, its angle relative to Earth and the sun, and the makeup of its icy nucleus. Each comet's heart is a clump of ancient solar system debris — a mix of dust, rock, and frozen gases, much like the particles that make up Saturn's rings.

As sunlight heats that nucleus, the ice vaporizes, releasing jets of gas and dust that form the comet's signature tail. In Comet Lemmon's case, early images show that its tail is made mostly of gas, giving it a faint bluish hue and a thin, straight appearance pointing directly away from the sun.

On the other hand, comets that are prodigious producers of dust, are the ones that are eye-catching because such dust tails appear much brighter. The dust tail is a flat sheet of material spread out in the plane of the comet's orbit with one edge immediately adjacent to the gas tail.

Many happy (comet) campers

To date, most of the reviews coming in concerning the comet's appearance have been very favorable.

Despite bright moonlight from October's full Supermoon, recent comet brightness estimates at the Comet Observation Database (COBS) indicate that Lemmon has been a relatively easy object to sight with good binoculars. As of Oct. 6, a consensus of the comet's brightness showed it hovering near magnitude +6.1. (The lower the figure of magnitude, the brighter the object. The brightest stars are magnitude 0 and +1. The threshold of naked-eye visibility under a dark, moonless sky registers at around +6).

The head or coma measures at around 8 minutes of arc, or roughly one-quarter the apparent size of the moon. Visually, the length of the tail is around 1 degree or twice the width of the moon; long-exposure photographs, however, show the faint gas tail to be many times longer.

When and where to look

Currently, comet Lemmon is a morning object. In order to see it, you'll have to get up before dawn breaks — about 90 minutes before sunrise. The comet is currently passing through the southern boundaries of Ursa Major, the Great Bear. "This comet is developing very nicely and it is already an impressive object, well-placed for observation in the morning sky," Nick James, director of the Comet Section of the British Astronomical Association, told Spaceweather.com. "It is definitely worth getting up for!"

The full moon on Oct. 6 made spotting faint objects difficult, but visibility will improve as the moon wanes. After last quarter on Oct. 13, the moon becomes a slim crescent, allowing much darker skies for comet viewing.

Thursday morning, Oct. 16, will provide a great opportunity to locate comet Lemmon thanks to its proximity to a conspicuous star. That star is Cor Caroli, the brightest star in the constellation of Canes Venatici, the Hunting Dogs. Cor Caroli shines at magnitude +2.8 and on Oct. 16, the comet will be situated just 1° (two moon widths) above that star. Ninety minutes before sunrise, look for the Big Dipper, which will appear to be standing upright on its handle in the northeast sky.

Now draw an imaginary line diagonally through the Dipper's bowl from Dubhe (the upper right star in the bowl) down through Phecda (the lower left star in the bowl) and extend that line downward about twice the distance between those two stars and that will bring you to the vicinity of Cor Caroli. Aim your binoculars toward this star and Comet Lemmon will be situated just above.

Transition to the evening sky

Oct. 16 is also the date when the comet will become available to evening skywatchers. In fact, Lemmon will likely put on its best show between Oct. 22 and Oct. 28, low in the west-northwest sky right after the end of evening twilight. During that timeframe, the comet will be tracking rapidly through the constellation Boötes the Herdsman and into Serpens the Serpent on Oct. 24. Around the end of twilight, it will sit about 15° above the horizon, roughly one and a half fist-widths at arm's length.

On the evening of Oct. 22, the comet will lie about 2° left of the star Izar (Pulcherrima), a beautiful double star with a yellow-and-blue color contrast often described as golden and sea green.

Oct. 22 through Oct. 28, will also be when the moon will not be much of a factor, being no worse than a waxing crescent phase. This will also be the time when comet Lemmon is expected to shine at its brightest.

Japanese comet expert Seiichi Yoshida thinks the comet will peak at around +4 magnitude, but Dutch comet expert Gideon Van Buitenen has recently revised his brightness forecast, indicating that the comet might get as bright as magnitude +3.3, which would make it evident with the naked eye against a dark sky. "I think we can now be reasonably confident that this will be a very nice evening object when it is at its brightest around New Moon in late October," adds James.

Final thoughts

Those blessed with very dark skies might even be able to continue following with just their unaided eyes until the first week of November. Of course, the comet could always dim much more rapidly, or a sudden, unexpected flare-up could also occur. But these are extreme cases. So far, the comet has performed very well and there is no reason not to believe that it will continue to delight Northern Hemisphere observers for a few more weeks.

Once again, we should stress that the darker your observing site, the better the comet will appear. With the bright moon pretty much out of the way during the second and third weeks of April, prospective comet observers are likely to have their greatest success.

Good luck and clear skies!

For more information on how you can photograph and comets for yourself, check out our comet skywatching guide.

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.

Editor's Note: If you would like to share your photos of Comet Lemmon (C/2025 A6) with Space.com's readers, then please send your photo(s), comments, and your name and location to spacephotos@space.com.

Comet C/2025 A6 (Lemmon) is just weeks away from a close approach to Earth that could make it visible to the naked eye in the October night sky. Read on for spectacular views of this wandering comet and its magnificent tail as captured by astrophotographers around the world.

Astronomers discovered Comet C/2025 A6 (Lemmon) on Jan. 3 using a 60-inch telescope located at the Mt.Lemmon Observatory in Arizona. The comet is currently heading farther into the solar system and will make its closest approach to Earth on Oct. 21, passing a little over 55 million miles (89 million kilometers) from our planet, before heading on to perihelion — its closest point to the sun — on Nov. 8.

Since its discovery, the comet has brightened significantly, jumping from magnitude +21.5 in January to +7 and beyond, raising hopes that it could become visible to the naked eye from dark sky locations in the coming month if the trend continues. Remember, magnitude is the scale used by astronomers to chart the apparent brightness of an object in the night sky. The lower the number, the brighter the object. The human eye is able to see bodies with a magnitude of +6.5 under ideal dark sky conditions.

Comets are famously unpredictable. The recent brightening could be a transient outburst rather than a steady increase as the comet approaches to the sun, only time will tell.

Right now, the wandering solar system body is currently visible as a diffuse smudge of light through binoculars, while astrophotographers using specialized cameras attached to powerful backyard telescopes are already capturing breathtaking long-exposure views of the comet's bright nucleus and twisting ion tails.

Comet C/2025 A6 (Lemmon) in pictures

Astronomer Aleix Roig captured this image of Comet Lemmon in the moonless skies above Catalonia, Spain, on Sept. 22, revealing the haunting glow of the central coma from which flows a spectral ion trail.

"In this image, you can clearly see the comet's greenish coma, a result of diatomic carbon (C2) fluorescing in sunlight and its developing tail extending away from the Sun," Roig wrote in a blog post on his astronomy website www.astrocat.info. "These features make "Lemmon" a striking reminder of the icy wanderers that visit the inner solar system from the distant Oort Cloud."

Jānis Šatrovskis stitched together a stunning timelapse view revealing the extent to which C/2025 A6 (Lemmon) traveled relative to the starfield beyond just a few days later on Sept. 25 from Burtnieki, Latvia.

Even more detailed views came courtesy of astrophotographer Dan Bartlett, who imaged the comet over multiple nights to reveal how the complex structure of its ever-shifting tail evolved over time from his backyard in June Lake, California, over recent weeks. Bartlett captured the comet's twisting ion tail wax and wane as it was buffeted by the solar wind emanating from our parent star.

Chris Schur produced a spectacular hour-long exposure of Comet Lemmon over Payson, Arizona, on Sept. 30.

"While Comet Lemmon was merely a soft diffuse glow in the binoculars, long exposure imaging revealed a stunning object with a lovely teal colored head turning into a pair of tails - one golden hued made of dust near the head, and a long blue streamer of gas traveling all the way across my 3 degree wide field with the 8inch astrograph," Schur told Space.com in an email.

X user Bray Falls captured yet another gorgeous view of C/2025 A6 (Lemmon) streaking through the skies above Austin, Texas, in early October as the tail showed subtle perturbations brought about by the solar wind.

Chuck's Astrophotography posted a similarly magnificent view on X, showing incredible detail in the tail as it sprawled out against a backdrop of distant stars on Oct. 2

Comet Lemmon is best viewed in the hours preceding dawn in early October and can currently be found between the constellations Ursa Major and Leo Minor. Following perihelion on Nov. 8, Comet Lemmon will embark on a 1,351-year elliptical orbit that will see the icy body range out 243 times the Earth/sun distance before beginning its return journey to the inner solar system.

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

In the coming weeks, skywatchers will have an opportunity to view a new comet that is currently inbound on its way toward the sun. This new visitor to the inner solar system is expected to brighten, perhaps becoming a fairly easy object to see in small telescopes or good binoculars.

And there's hope that it may even become bright enough to glimpse with the naked eye under dark non-light polluted skies (for those who have access to such viewing sites).

The new comet is catalogued as C/2025 A6 (Lemmon). It was discovered by the Mount Lemmon Survey, utilizing a 60-inch (1.52-meter) Cassegrain reflecting telescope, equipped with a 10560 x 10560-pixel camera. The telescope is located at the Mount Lemmon Observatory and is operated by the University of Arizona's Steward Observatory located in the Santa Catalina Mountains to the northeast of the city of Tucson.

The Mount Lemmon Survey (MLS) continuously scans the sky looking for near-Earth objects  — asteroids or comets  — whose orbits bring them within a certain distance of the sun and potentially Earth's orbit, meaning they can pass close to our planet. The vast majority of MLS's discoveries have been of asteroids (to date more than 50,000), but every so often the survey will catch sight of a new comet, as is the case with C/2025 A6.

Originally, when first photographed by astronomer David Fuls on Jan. 3, it was believed that the MLS had found yet another asteroid. It appeared as nothing more than a tiny starlike speck of light with a magnitude of +21.5; that's one million times dimmer than the faintest star on the threshold of naked-eye visibility. Follow-up images showed the object to be, in fact, a comet, and an even fainter pre-discovery image was located dating back to November 2024.

An orbit based on 117 observed positions between Nov. 12, 2024 and Aug. 14 has been calculated by Syuichi Nakano of the Central Bureau for Astronomical Telegrams. Nakano found that the comet will pass perihelion — its closest point to the sun — on Nov. 8 at a distance of 49.25 million miles (79.25 million km). It will come closest to Earth (its perigee) on Oct. 20 when it will be 55.41 million miles (89.16 million km) away.

Welcome back!

Comet Lemmon has apparently been here before. Mr. Nakano's orbital computations indicate that at the far end of its orbit (aphelion), it is situated as far as 22.6 billion miles (36.3 billion km) from the sun. Its orbital period is estimated at approximately 1,350 years. However, back on April 16, the comet passed within 216.6 million miles (348.5 million km) of Jupiter. That giant planet's gravitational field served to sap some of comet Lemmon's orbital energy and as such will shorten its period by some 200 years.

We know that comets are composed primarily of frozen gases that are heated as they approach the sun and made to glow by the sun's light. We call this cloud of gas the head or coma.

As the gases warm and expand, particles of dust that were embedded in the comet's nucleus are also released into space. The solar wind blows this material out into an appendage we call the tail. To observers of antiquity, comets resembled a stellar head trailed by long hair, so they called comets, "hairy stars."

Bright among "common" comets

Comets can be broken down into two basic categories:

Bright comets — the kind that can excite those of us without binoculars or telescopes — appear on average perhaps two or three times every 15 to 20 years. The last such comet to do that was this past January with comet C/2024 G3 (ATLAS), nicknamed the "Great Comet of 2025."

Then there are the common comets, of which most are only visible either with good binoculars or a telescope. The vast majority of comets fall into this category, but comet Lemmon may end up ranking as rather bright so far as most common comets go, since for a short while it may hover right around the cusp of naked-eye visibility (for those fortunate enough to be blessed with dark, non-light polluted night skies).

How bright?

A number of different predictions have been made regarding the brightness of Comet Lemmon as it passes closest to Earth during the third week of October. To date, the most optimistic brightness forecasts are those issued by Japanese comet expert Seiichi Yoshida and Dutch comet expert Gideon Van Buitenen. Both are projecting that the comet will peak somewhere between magnitude +4 and +5, meaning it might become faintly visible with the unaided eye sometime during early October.

Other forecasts, however, are far more conservative. Daniel W.E. Green at the Central Bureau for Astronomical Telegrams, on circular #5594, issued on Aug. 20, "cautiously" suggests a peak magnitude of +7.3 on Oct. 27. That would make it too faint to be seen with bare eyes alone, but certainly within reach of good binoculars or small telescopes.

Where to find it and viewing prospects

Right now, comet Lemmon is a predawn object, located in the faint zodiacal constellation of Cancer. It will cross over into the similarly vague and dim constellation of Lynx on Sept. 9 at a declination near +34°. It will still be quite faint, probably no brighter than magnitude 9 or 10. But from then onward, its brightness and movement against the background stars will progressively increase eastward as it approaches Earth.

For most, the first really good opportunity to try and make a definitive sighting will come on the morning of Oct. 6, when it will move into the southern boundaries of the Great Bear, Ursa Major. On this morning, Comet Lemmon will be passing less than 0.3 degrees to the upper left of the third-magnitude star Tania Australis, a member of the three pairs of stars that mark "The Three Leaps of the Gazelle." Tania is part of the pair marking the second or middle Gazelle leap. It rises in the north-northeast shortly before 1 a.m. local daylight time and by the break of dawn will be one-third up in the east-northeast. The comet will be in the same field of view and could be as bright as magnitude +6 or +7, making it an easy target with binoculars.

Beginning Oct. 12, the comet will begin to be available to evening skywatchers, low in the northwest about 90 minutes after sunset.

On Oct. 16, the comet will be positioned about 1 degree to the upper left of the third magnitude star Cor Caroli in the constellation of Canes Venatici, the Hunting Dogs. At that time, comet Lemmon will be racing 4 degrees per day, so even a few minutes of watching with a telescope should reveal its shift relative to field stars.

On Oct. 22, about 7:30 p.m. local daylight time, look very low above the west-northwest horizon for the brilliant orange star, Arcturus in Boötes the Herdsman. On that same evening, comet Lemmon will be situated 10 degrees above this star (your clenched fist held at arm's length also measures 10 degrees in width). The comet will also be positioned about 2 degrees to the left of the second magnitude star Izar, also in Boötes. A quick check of Izar with binoculars should also reveal the comet.

Keep your expectations low

But as compelling as this all may sound; we now must temper any excitement by providing a very important disclaimer.

By early-to-mid October, many people with binoculars and small telescopes will no doubt attempt to follow the path of Comet Lemmon across the night sky. But seeing it will strongly depend on your observing site. From locations that are plagued by light pollution, sighting this comet may prove to be rather difficult. Remember, you're not looking for a sharp star-like object, but rather something which is spreading its light out over a comparatively large area.

In fact, under a completely dark sky, free of light pollution, perhaps the best instruments for locating the comet will be your own two eyes, especially if you use averted vision.

Recent photographs have shown the comet displaying a distinct greenish color, likely due to a molecule made from two carbon atoms bonded together, called dicarbon. This unusual chemical process is confined chiefly around the comet's head, not its tail. Comets generally throw off two types of tails; tails composed primarily of gas, and tails composed primarily of dust. Dust tails are far brighter and more spectacular to the eye than gas tails, because dust is a very effective reflector of sunlight.

Comet Lemmon's tail, however, appears to be primarily composed of gas. Such tails appear much fainter and glow with a bluish hue. The gas is activated by the ultraviolet rays of the sun, making the tail glow in much the same way that black light causes phosphorescent paint to light up.

So, most who ultimately locate Comet Lemmon in their binoculars or telescopes will typically describe it as a nearly circular cloud, appearing noticeably brighter and more condensed near the center. Some might also detect a faint tail appearing as a bit of an elongation of the comet's coma, but hardly the kind of tail or appendage exhibited by other larger and brighter comets.

A final point to consider: comets are notoriously unpredictable; we can only guess how they ultimately will appear in our sky. It's not completely out of the question that comet Lemmon could surprise us and become unexpectedly bright.

Then again, it might fail to brighten much at all, perhaps living up to the homonym of its name (a lemon). We'll post any updates if needed here on Space.com. So, stay tuned!

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.

Comet Lovejoy from Missouri

Skywatcher Victor Rogus took this photo from Jadwin, Mo. on Nov. 13, 2013.

Comet Lovejoy Near the Big Dipper

Located just off the handle of the Big Dipper in the constellation of Canes Venatici, comet Lovejoy is an easy binocular object at 5th magnitude. A bright, greenish coma and a tail are very evident in this three-minute exposure taken on the morning of Nov. 26 using a 6" Takahashi refractor located in New Mexico. At the time of this image, comet Lovejoy was 40 million miles from Earth and 88 million miles from the sun. It reaches perihelion (closest approach to the sun) on Dec. 22.

Comet Lovejoy Nucleus

Optical image of the structures surrounding the nucleus of the Comet Lovejoy, captured by FOCAS mounted on the Subaru Telescope. This image was taken in the early morning of Oct 31, 2013 in V-band (550 nm) with an exposure time of 5 seconds. The field of view is about 6 x 3 arcminutes. The lower-left inset shows the structures around the nucleus after adjusting the contrast in the image.

Comet ISON Photographed by Mike Hankey

Astrophotographer Mike Hankey sent in a photo of Comet ISON, taken on Nov. 10, 2013, from his location in Auberry, CA (near Fresno). He has been imaging ISON regularly since Sept 21 and noticed a more prominent jet in recent days.

Comet Linear 2012 X1 in Blue by John Chumack

Astrophotographer John Chumack sent SPACE.com this image of Comet Linear 2012 X1 taken on Oct. 28, 2013. “It reminds me of Comet Holmes from 2007,” Chumack wrote SPACE.com in an email. “It did the same thing and the coma expanded to become the largest thing in the solar system—larger than the sun!”

Comet Encke, Comet LINEAR, and Comet ISON by Scott MacNeill

Scott MacNeill of Frosty Drew Observatory sent SPACE.com this combination of three photographs captured on the morning of Oct. 26, 2013 from Frosty Drew Observatory in Charlestown, Rhode Island. The image shows Comet 2P Encke, Comet 2012 X1 LINEAR, and Comet 2012 S1 ISON.

Comet Lovejoy Seen in Long Island, NY

Observer Frank Mellilo took this photo of Comet Lovejoy from his home on Long Island.

Comet Linear 2012 X1 Inverted Image by John Chumack

Astrophotographer John Chumack sent SPACE.com this image of Comet Linear 2012 X1 taken on Oct. 28, 2013. “I managed a couple of quick shots before my CCD was flooded completely with light!” Chumack wrote SPACE.com in an email.

Comet Linear 2012 X1 by John Chumack

Astrophotographer John Chumack sent SPACE.com this image of Comet Linear 2012 X1 taken on Oct. 28, 2013.

Comet ISON by Scott Ferguson

Scott Ferguson captured this image of Comet ISON on Oct. 27 while at a friend's private observatory, Northwest Florida Observatory. He used a 20" Meade LX400-ACF Max Mount and Televue NP101 to capture the photo, which was sent to SPACE.com on Oct. 30.

Comet ISON Photographed by Adam Block

Adam Block of the Mt. Lemmon SkyCenter (University of Arizona), sent in another image of Comet Ison, taken Nov. 8, 2013. He writes in an e-mail message to SPACE.com: "This is exactly one month after the previous picture I captured. It is now significantly brighter (unfortunately not yet visible to unaided eyeballs). However, it is also moving much more quickly so that capturing it at this image scale is a bit tricky. Very soon it will head into the glare of the sun. Hopefully we can monitor it via images from space-based solar telescopes as it rounds the sun at the end of the month."

Comet ISON Nucleus on Oct. 9

John Chumack sent SPACE.com this photo of comet ISON’s nucleus taken on the morning of Oct. 9 from his dark-sky site at John Bryan State Park in Yellow Springs, Ohio. “I’m excited to see what comet ISON will do in the next 60 days,” he wrote SPACE.com in an email. He used a QHY8 cooled single shot color CCD camera and his homemade 16" Diameter F4.5 Newt. Telescope to take the image.

Comet Pan-STARRS on March 2, 2013

Astrophotographer Luis Argerich of Buenos Aires, Argentina, took this photo of Comet Pan-STARRS taken on March 2, 2013. He writes: "Easy to see with the naked eye from rural locations."

Comet Pan-STARRS C/2011 L4

Comet Pan-STARRS C/2011 L4, discovered by the Pan-STARRS 1 telescope on Haleakala in June 2011, is expected to become visible to the naked eye in the Northern Hemisphere in March. The comet is currently visible in the Southern Hemisphere.

Comet Lemmon Seen in New Zealand

Astrophotographer John Drummond sent in his photo of Comet Lemmon taken on Jan. 23, 2013, in New Zealand.

Comet Pan-STARRS Seen in Buenos Aires

Astrophotographer Luis Argerich of Buenos Aires, Argentina, took this photo of Comet Pan-STARRS taken on March 2, 2013. He writes: "While the tail was still short it was easy to see with the naked eye and very bright."

Comet Lemmon Seen in Auckland, New Zealand.

Brent Russell of SkySlab Observatory, Auckland, New Zealand, provides this photo of Comet Lemmon taken Feb. 17, 2013. He writes: "Currently it is binocular visible in the city suburbs, not naked eye."

Comet Pan-STARRS Telescope Photo

A telescope photo of comet Pan-STARRS, which may become visible to the naked eye in March 2013.

Comet Pan-STARRS Seen in Buenos Aires #2

Astrophotographer Luis Argerich of Buenos Aires, Argentina, took this photo of Comet Pan-STARRS taken on March 2, 2013. He writes: "Comet Pan-STARRS was visible from about 8:15 pm to 9 pm above the western horizon."

Comets Lemmon and Pan-STARRS Together at Last

Astrophotographer Justin Tilbrook of Penwortham, South Australia, caught this photo of Comets Lemmon (bottom left) and Pan-STARRS (right near the Small Magellanic Cloud) together on Feb. 17. 2013. He writes: "This is the one I've been waiting for…. Don't mind saying it was difficult to set this up, a narrow window before sunrise, 4 degrees of hill in the way, limitations with the dome slit and having to mount the camera at the front of the scope at a very odd angle. Took about an hour."

The Comet and the Laser

ESO’s Very Large Telescope (VLT) tested a new laser for the VLT on Feb. 14, 2013. To the right of the centre of the image, just below the Small Magellanic Cloud, streaks comet Lemmon.

Comet C/2011 L4 (PANSTARRS) Discovered by Asteroid Telescope

Discovery image of the newfound comet C/2011 L4 (PANSTARRS), taken by Hawaii's Pan-STARRS 1 telescope.

Comet C/2012 S1 (ISON)

The comet that may put on a spectacular light show during a November date with the Sun, was observed by the Deep Impact mission. The spacecraft has also had close fly-bys of comet's Tempel 1 and Hartley 2 and scientific observations of Garradd.

Comet ISON in Telescope View

This still from a NASA video identifies comet C/2012 S1 (ISON), better known as Comet ISON, in a telescope image.

Comet ISON in Night Sky

Skywatcher Vernon Dye took this shot of Comet ISON on Jan. 8, 2012. Comet ISON c/2012 S1 is currently in the Constellation of Gemini, moving between the head of the Twins Castor and Pollux.

Newly Discovered Comet C/2012 S1 (ISON)

This image shows the newfound comet C/2012 (ISON) as seen by the Remanzacco Observatory in Italy. The image, taken by amateur astronomers Ernesto Guido, Giovanni Sostero and Nick Howes, is a confirmation view of the comet, which was first discovered by Vitali Nevski (Vitebsk, Belarus) and Artyom Novichonok (Kondopoga, Russia). Image released Sept. 24, 2012.

Comet ISON Seen by Messenger Probe on Nov. 19, 2013

Image of comet ISON taken by NASA's Messenger probe during its closest approach to Mercury on Nov. 19, 2013. At that time, ISON was approximately 22.5 million miles (36.2 million kilometers) from Messenger and 42.1 million miles (67.8 million km) from the sun.

NASA Releases Comet ISON Images from STEREO

Comet ISON entered the view of NASA's Solar Terrestrial Relations Observatory on Nov. 21, 2013, where it can be seen with Earth, Mercury and comet 2P/Encke.

Comet 2P/Encke During Closest Approach to Mercury

This Messenger spacecraft image shows comet 2P/Encke during its closest approach to Mercury. At that time, Encke was approximately 2.3 million miles (3.7 million kilometers) from Messenger and 32.7 million miles (52.6 million kilometers) from the Sun. The tail was oriented nearly side on to Messenger in this image and is seen to stretch several degrees from the comet’s bright coma in the direction away from the Sun. This image was released Nov. 25, 2013.

Veteran astrophotographer Terry Hancock was pleasantly surprised to learn the uninvited guest in his recent photo was not an aircraft, but rather Comet Lemmon soaring across a nebula-filled night sky.

"I was oblivious to the fact that Comet Lemmon was visiting this neighborhood," Terry Hancock wrote SPACE.com in an email. "When I processed this at first I thought I had captured aircraft lights."

The image features M52 Cluster (top center), the Bubble Nebula NGC7635 (left of center), the emission and reflection nebula NGC 7538 (lower central area) and Sharpless 157, also known as the Lobster Claw Nebula (bottom left), and Comet Lemmon (upper right).

Hancock took the image over 8.5 hours on July 14 and 15 from DownUnder Observatory in Fremont Mich. To capture the photo, Hancock used a QHY11 monochrome CCD camera, QHY Color Filter Wheel, TMB92SS F5.5 APO Refractor with TS 2.5" Field Flatteneroptics, Paramount GT-1100S German Equatorial Mount (with MKS 4000), and image acquisition software Maxim DL5.

Alex Gibbs of the Mount Lemmon survey in Arizona discovered Comet Lemmon, or C/2012 F6, in March 2012. Since its discovery, the comet has become increasingly brighter in the night sky as it makes its way through the solar system.

Comet Lemmon is officially known as Comet C/2012 F6 and is one of several comets that have graced the night sky in 2013. Comet Pan-STARRS (C/2011 L4) gave stargazers a celestial show earlier this year in March, and the Comet ISON — officially dubbed C/2012 S1 (ISON) — is expected to be at its best in the night sky in late November.

Editor's note: If you have an amazing night sky photo you'd like to share for a possible story or image gallery, please contact managing editor Tariq Malik at spacephotos@space.com.

Follow SPACE.com on Twitter @Spacedotcom. We're also on Facebook & Google+.

The dazzling Comet Lemmon has recently been taking center stage for those gazing up at the night sky south of the equator. 

Astrophotographer John Drummond took this photo on Jan. 23, 2013, from Gisborne, New Zealand. He used a 41cm f5.2 Meade Newtonian Telescope to view the comet and a Canon 500D DSLR camera, with settings at 20 x 1 min., FOV = ~43' x 27' to capture the image.

"It’s been a joy to watch it slide through crux with binoculars. It was the hit at our summer national star party! A tail isn’t obvious, but hints of one are picked up photographically. It’s a nice, bright large blob in telescopes," Drummond wrote SPACE.com in an email

"Over time it will head north and will be too far north for us New Zealanders to see it from about the end of May 2013."

Comet Lemmon, or C/2012 F6 as it is officially known, was discovered by Alex Gibbs of the Mount Lemmon survey in Arizona in March 2012. At that time, it was very faint in the sky. However, the comet has made its way into the inner solar system and is getting brighter in the sky. It will be at its closest point to the sun, or perihelion, on March 24.

Comet Lemmon is not the only comet in the night sky promising to dazzle stargazers this year. In March, the Comet C/2011 L4 (PANSTARRS) — sometimes referred to as Comet Pan-STARRS — is expected to brighten into a naked eye object that could make it a striking site in the sunset sky.

In late November the bright Comet C/2012 S1 (ISON), is expected to put on a dazzling display in the night sky. The comet will be closest to the sun on Nov. 28 and closest to Earth in late December

Editor's note: If you have an amazing photo of comets Lemmon, Pan-STARRS or ISON that you'd like to share for a possible story or image gallery, please send images and comments to managing editor Tariq Malik at spacephotos@space.com.

Follow SPACE.com on Twitter @Spacedotcom. We're also on Facebook & Google+.