COMET ALERT! TWO AMAZING COMETS CURRENTLY VISIBLE IN OUR NIGHT SKIES!

If you have been following astronomy news recently, as well as the incredible interstellar object 3I/ATLAS, you may have heard about another two very special icy visitors to our inner solar system – namely the two comets C/2025 A6 LEMMON and C/2025 R2 SWAN. 

Both of these comets have been amazing astro-imaging targets for a little while now, but both are also now fairly easily visible in our night skies with the aid of binoculars or telescope. Both comets can be fairly easily picked up in long exposure DSLR/mirrorless photographs, and for those blessed with good eyesight and dark skies, they may also be just about visible to the naked eye too! The two comets are predicted to become easier to spot as they near perigee (their closest aproach to the Earth), and A6 Lemmon is predicted by some sources to possibly become bright enough to be fairly easy to spot with the naked eye as it travels closer to the Sun. This means (if the horrible cloudy weather we have been enduring actually clears sometime soon) the next few nights will be an excellent time to view these once in a lifetime visitors to our inner solar system! 

It is a very rare occurrence to have two bright comets visible at the same time and so for comet hunters and average night sky enthusiasts alike, October is a very exciting time indeed. Not only this, both comets closest approach to the Earth will be around the 21st of October, which is also the date the Moon reaches its new phase. This means that viewing conditions (clouds aside) will be excellent for comet observation. In addition to all of this, both comets’ closest approach plus the New Moon will also coincide with the most active period of the Orionid meteor shower. And so, if we have clear skies in the near future, we could be in for some very special nights of comet watching, and meteor watching! Very exciting stuff indeed! However, it should be noted that comets are notoriously unpredictable, and only time will tell how they develop. 

For more information on the Orionid meteor shower, please read our separate Orionid meteor shower post. 

If you would like more information on both of these amazing once in a lifetime icy visitors, what comets are, plus hints and tips on how best to see them please read on… 

Comet A6 Lemmon was discovered on the 3rd of January 2025 by astronomer David Fuls whilst working on the Mount Lemmon Survey. The Mount Lemmon Survey is a program operated by the University of Arizona’s Steward Observatory, that uses a 1.5 meter telescope at the Mount Lemmon Observatory in Arizona to detect near-earth objects. The comet was named after the observatory where it was discovered. 

By studying observations of the comet, scientists calculated its orbit and found that A6 most likely last visited the inner solar system over 1000 years ago, possibly during the middle ages. 

A6 Lemmon will reach perigee (closest approach to the Earth) on the 21st of October, after it passes by Earth it will travel closer to the Sun and reach perihelion (closest approach to the Sun) on the 8th of November. The comet was reported to be around magnitude 6 in early October, which places it just at the edge of visibility by the naked eye under perfect conditions. However, some sources have predicted that as the comet moves closer to the Sun it may reach an apparent magnitude of as bright as 2.5! This would mean the comet would quite easily be visible by eye under good conditions. 

Comet A6 Lemmon makes an appearance in the early evening skies and briefly in the early morning skies at this moment in time, but is easiest to observe during the early evening above the North-Western horizon just as darkness falls. We recommend trying to observe this comet between 19:30 and 21:30 BST before the comet appears too low on the horizon to be easily observed. 

Comet A6 Lemmon is currently located within the boundaries of the constellation of Bootes which can be found to the left of the famous asterism of “the Plough”. On each consecutive night, the comet will appear slightly further to the left, travelling across Bootes between the 20th and 23rd of October, and moving into the constellation of Serpens Caput on the 24th of October. The comet is predicted to become brighter as it moves closer to the Sun throughout October and so may become easier to spot as the month progresses, however it will appear lower on the horizon too. 

To stand a better chance of observing this comet you may need the help of a pair of binoculars or a telescope. The comet should also stand out in long exposure photographs aimed to the North-West. A nice clear view of the West to North-Western horizon with as little light pollution in that direction will help you in observing the comet. 

A useful marker to help you locate A6 Lemmon is the bright star Arcturus of the constellation Bootes. Arcturus is the fourth brightest star in the sky and can be easily found by tracing an arc from the end of the “tail” of Ursa Major (or the handle of the plough) to the nearest bright star (this is Arcturus). With your binoculars or telescope, try scanning the area of sky around 10 degrees above and right of Arcturus between the 20th-21st and above and left from the 22nd onwards, and you might be able to spot a fuzzy smudge of light (if you are lucky you might also be able to see a hint of the tail), this will be comet A6 Lemmon. 

Comet R2 SWAN was discovered by Ukranian astronomer Vladimir Bezugly on the 11th of September via observation of images taken from the SWAN instrument onboard the Solar and Heliospheric Observatory (SOHO). After its discovery, it was found that images of the comet went back to 13th of August. It was named after the instrument that it was discovered with. 

The comet reached perihelion (its closest approach to the Sun) on the 12th of September. And will reach perigee (its closest approach to Earth) today, on the 20th of October. R2 SWAN was reported to have reached an apparent magnitude of 6.2 on the 16th of September, and was reported in late September to have reached an apparent magnitude of 5.9 due to an outburst from the comet. Some sources have predicted that it may reach a magnitude of between 4 and 6 around perigee which would make it visible to the naked eye under dark skies. 

Comet R2 SWAN can currently be observed above the South-Western horizon in the early evening just as darkness falls. We recommend trying to observe this comet between 19:30 and 22:00 BST before the comet appears too low on the horizon to be easily observed. 

Comet R2 SWAN is currently located within the boundaries of the constellation of Sagittarius just above the asterism the “teapot” and below the constellation of Aquila. Each consecutive night, the comet will appear slightly further to the left, travelling through the boundary of Aquila between the 21st and 25th of October, moving into the constellation of Aquarius on the 26th of October. 

To stand a better chance of observing this comet you may need the help of a pair of binoculars or a telescope. The comet should also stand out in long exposure photographs aimed to the South-West. 

If you can locate the bright star Altair of the constellation Aquila, try scanning the area of sky around 20 degrees below Altair with your binoculars or telescope and you might be able to spot a fuzzy smudge of light (if you are lucky you might also be able to see a hint of the tail), this will be comet R2 SWAN. If you are familiar with the asterism known as the “Summer Triangle”, Altair is the bright star located at the bottom of the triangle. 

Comets are large pieces of ice, rock and dust that travel from the outer reaches of the Solar System into the inner Solar System, past the Sun and then back outwards again. These icy visitors sometimes come from the Kuiper Belt, a ring of icy and rocky objects, located just beyond the most distant planet Neptune’s orbit. Other comets have travelled from even further! Some comets are thought to come from the ‘Oort Cloud’: a hypothetical, spherical cloud of objects that surrounds the Solar System located hundreds of billions of miles away from the Sun. 

As comets travel close to the Sun, the ice melts and evaporates. Some of the released gasses create a hazy looking cloud around the nucleus, this is called a ‘coma’. The rest of the comet’s contents are blown away by solar wind which creates two trails made of dust and gas that always flow away from the Sun. Some comets may also contain large amounts of gaseous elements that become ionised and create colourful glows of emitted light. 

Comets are worth the effort to try and see because many are once in a lifetime sights. Halley’s Comet visits our planet once every 75-76 years. It is thought that C/2025 A6 Lemmon may not be visiting us again for another 1,300 years, and C/2025 R2 SWAN may not be back for another 22,000 years! 

• Find a safe location with a clear unobstructed views of the West to North-Western horizon for A6 Lemmon and towards the South to South-West for R2 SWAN. 

• Both comets have been reported to currently visible to the naked eye under perfect dark skies, but should be fairly easy to observe with a pair of binoculars, a telescope or a camera. 

• The best time to view both comets may be between 19:30 and 22:00 BST for both comets but you may want to head out and start observing a little earlier. 

• The best date to observe the comet R2 SWAN may be this evening, the 20th of October as the comet will likely continue to fade in brightness as it travels away from the Sun. 

• Although it may be a good time to spot A6 Lemmon from tonight, it may become much brighter and easier to spot as the month progresses. And so if you can, we recommend trying to observe this comet each night throughout the rest of October. 

• A good astronomy app that shows you the location of comets such as Stellarium, may help you find the location of the comets in the sky. 

• Dress warm! It can get very cold comet hunting, so make sure to dress well to stay comfortable. You may wish to bring a flask with a hot drink for extra comfort. 

If you would like to know more about the rest of the celestial treats that can be seen in the skies throughout this October, please head to our YouTube channel to watch our Night Sky Guide video for October 2025. 

SHARE YOUR EXPERIENCES AND PHOTOGRAPHS!

We always love hearing about your celestial adventures and seeing your photographs! If you head out to witness or take photographs of this special celestial event or any other sights in the night sky, please feel free to share your stories and photos in the comments below. 😊

We wish you luck if you head out to try and view these amazing, once in a lifetime, icy visitors from the outer Solar System.

Good luck and clear Skies! 💖

#comets #comet #a6lemmon #r2swan #astronomy