A pair of once-in-a-lifetime comets will rocket through our skies this October. It’s a rare treat for skywatchers, as they won’t be back again for hundreds of years.
The comets — C/2025 A6 (Lemmon) and C/2025 R2 (SWAN) — look similar from our perspective. You can spot these green gaseous globes and their streaming tails now. But the comets will be even easier to see later this month.
SWAN will shine the brightest around Oct. 20, NBC News reports. Just a day later, on Oct. 21, Lemmon will make its peak showing in the dark sky.
If you want to witness these comets shooting past Earth, the coming weeks will be the best time. There won’t be another chance; the next time SWAN will come by again will be in 650 to 700 years, and Lemmon won’t return for another 1,300 years, CNN reports.
Comets are known to buck even the most careful predictions, but wary observers might catch these rare spectacles in October from their backyards in the pre-dawn morning or night sky.
New comets on the scene
Lemmon and SWAN were both discovered in 2025. Lemmon was discovered on Jan. 3 in Arizona by the Mount Lemmon Survey — using a 60-inch telescope installed on Mt. Lemmon to find celestial objects — which lent the comet its name.
“Current models are showing the comet will likely peak between 3.5 and 4.5 magnitudes when it is nearest to Earth on October 21, which is dimmer than what they showed last week,” Saint Louis Science Center wrote in an October update. “This is still bright enough that it could become naked-eye visible from light-polluted locations.”
A Ukrainian amateur astronomer named Vladimir Bezugly discovered the SWAN comet on Sept. 11 while he was looking through images captured by SWAN, a science instrument called Solar Wind ANisotropies, which is installed on the Solar and Heliospheric Observatory in space.
“It was an easy comet for detection due to sufficient brightness in the (ultraviolet) band and location in the SWAN images, exactly in its center,” Bezugly told Universe Today. He also noted it’s the 20th official SWAN comet so far.
How to see Lemmon and SWAN this October
The darker the night sky, the easier it will be to see comets, moons, planets and stars. If you live in a city, bundle up and take an evening skygazing trip to the country where there’s less light pollution, with blankets, chairs and something warm to drink.
It takes a while for your eyes to adjust to the darkness. Find a comfortable spot where you can stay still and gaze up. The comets might be bright enough to see without aid, but NASA recommends binoculars as a great entry-level stargazing tool.
Telescopes are one of the best ways to skygaze, and you might be able to find one to use or rent at your local library or university. But modern telescopes can also be fairly affordable.
Smartphone apps can also be helpful when trying to identify celestial phenomena and where to find them. Check out our list of stargazing apps for a few recommendations.
A sky full of wonders
Aside from the newly discovered comets, skywatchers have a few other cosmic treats to enjoy this month.
The Orionids meteor shower — when Earth travels through the massive tail of Halley’s Comet — began earlier this month, but you’ll be able to see the meteors through the beginning of November.
The next supermoon, known as the beaver moon, will take place on Nov. 5.
