Topline
This week brings a final chance to easily see Comet Lemmon (C/2025 A6) and perhaps the dimmer Comet SWAN (C/2025 R2) about 90 minutes after sunset from the Northern Hemisphere. Both comets can be seen using binoculars, in the northeast and southwest, respectively. On Tuesday, Oct. 28, 2025, both comets will be in their post-closest approach phase and drifting farther from Earth, with Lemmon closing in on its perihelion on Nov. 8, when it will swing closest to the sun. Although fading, both comets remain visible in binoculars both before dawn and after sunset under dark skies, but with the moon close to first quarter, the night sky will soon brighten.
Key Facts
Comet Lemmon can be found west of the Big Dipper, beyond bright star Arcturus, while Comet SWAN is moving towards Saturn, and is presently beneath Altair, the bright star at the tip of the famous Summer Triangle. The best time to look is 90 minutes after sunset.
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. It will return to the inner solar system in about 1,150 years.
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 Tuesday, Oct. 28, 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 5:53 p.m. EDT, the ideal time for evening viewing is 7:23-7:53 p.m. EDT. A 43% waxing crescent moon will begin to get in the way of comet-watching, brightening the sky, and on the cusp of effectively ending the reign of the comets in the post-sunset sky.
How To Find Comet Lemmon
Distance from the sun: 54.9 million miles (88.4 million kilometers)
Distance from Earth: 63.5 million miles (102.2 million kilometers)
After sunset on Tuesday, Oct. 28, look for Comet Lemmon due west in the constellation Serpens, “The Serpent.” It will be above-left of bright star Arcturus. Use bright star Vega, high up above the west, to guide you to Comet Lemmon, directly below. The comet’s height above the horizon varies by location, but from New York, the comet will appear about 20 degrees up at 7:23 p.m. EDT and will gradually sink as twilight deepens.
How To Find Comet Swan
Distance from the sun: 102.8 million miles (165.5 million kilometers)
Distance from Earth: 28.9 million miles (46.5 million kilometers)
Comet SWAN will be visible in binoculars on Tuesday, Oct. 28, 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 roughly between Altair and Fomalhaut. Perhaps an easier way to find it is to imagine a diamond shape with Saturn, Fomalhaut, the moon and Comet SWAN as the points.
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. However, the presence of a bright moon may make finding Comet SWAN difficult.
How Long Will The Comets Be Visible For?
Both comets will be visible through binoculars from the Northern Hemisphere until early November 2025 (peak brightness was Oct. 20-27). After that, they will fade as they recede from Earth, though observers in the Southern Hemisphere will finally see them around that time, according to Sky & Telescope.
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.
