Topline
If you’ve not seen the two green comets yet, 90 minutes after sunset on Sunday, Oct. 26, is your last best chance before they fade. The brighter Comet Lemmon (C/2025 A6) and much dimmer Comet SWAN (C/2025 R2) are now barreling away from Earth, reducing in brightness as they do, while a 24%-lit waxing crescent moon is on the cusp of making comet-observing significantly more difficult. With Lemmon in the northwestern sky and SWAN below the Summer Triangle stars in the south, near Saturn, it’s time to grab a pair of binoculars and take a look — or wait for 1,150 years.
Key Facts
Comet Lemmon is moving quickly west of the Big Dipper, near bright Arcturus, while Comet SWAN lies beneath the three stars that form the Summer Triangle. About 90 minutes after sunset is when to look for both.
Use stargazing apps such as Sky Guide, Stellarium and SkySafari, or finder charts at In-The-Sky.com. Each appears as a diffuse, fuzzy patch with a faint tail through binoculars (8×42 or 10×50 are the recommended sizes).
Comet Lemmon was discovered on Jan. 3, 2025, by the Mount Lemmon Survey near Tucson, Arizona, and will reach its closest point to the Sun on Nov. 8.
Comet SWAN was found on Sept. 11, 2025, as it looped around the Sun. Lemmon last visited the inner solar system in AD 875 and will return around 3175, while SWAN takes roughly 20,000 years to complete one orbit.
When And Where To See The Comets
The best time to spot Comet Lemmon and Comet SWAN on Sunday, Oct. 26, is during a 30-minute window starting about 90 minutes after sunset where you are. Both are visible after sunset but in opposite parts of the sky — Lemmon in the northwest, SWAN in the southwest. For New York City, where sunset is at 5:56 p.m. EDT, the ideal time for evening viewing is 7:26-7:56 p.m. EDT. A 24%-lit waxing crescent moon will be low in the southwest, setting early, so both comets benefit from dark conditions before the moon brightens later in the week.
How To Find Comet Lemmon
Distance from the sun: 56.9 million miles (91.6 million kilometers)
Distance from Earth: 59.8 million miles (96.2 million kilometers)
After sunset on Sunday, Oct. 26, look for Comet Lemmon due west, above-left of bright star Arcturus, low on the west-northwest horizon. Trace the stars in the Big Dipper’s curved handle and go in an “arc to Arcturus.” Now go in a right angle to the next bright star, Rasalhague, the brightest in the vast constellation Ophiuchus. Comet Lemmon will be directly below the bright star Vega, high above. Its height above the horizon varies by location, but from New York, the comet will appear about 21 degrees up at 7:26 p.m. EDT and will gradually sink as twilight deepens.
How To Find Comet Swan
Distance from the sun: 101.2 million miles (162.9 million kilometers)
Distance from Earth: 27.8 million miles (44.8 million kilometers)
Comet SWAN will be visible in binoculars on Sunday, Oct. 26, low in the south after sunset. SWAN will be in the constellation Aquarius, below and to the left of the bright star Altair in the Summer Triangle. You’ll find it between Altair and Fomalhaut, a bright star closer to the horizon. The comet’s height above the horizon will vary depending on your location, but from New York, it will be around 45 degrees up as it becomes visible.
Check my feed every day this month for a daily “comet tracker” with finder charts and tips for viewing Comet Lemmon and Comet SWAN from mid-northern latitudes. Also read How To Photograph The Green Comets, Best Stargazing Apps For Finding The Comets and 25 Dark Sky Parks In The U.S. To See The Comets.
