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Two green comets will reach their minimum distance from Earth, likely peak brightness, after sunset on Monday, October 20, just hours before the peak of the annual Orionid meteor shower, itself a product of Halley’s famous Comet. Comet Lemmon (also called C/2025 A6) and Comet SWAN (C/2025 R2) are coming closest to Earth early this week, at 55 and 24 million miles from Earth, respectively, and could be visible to the naked eye. So are the 20 or so “shooting stars” from the meteor shower. The rare celestial show will unfold under a new moon, ensuring dark skies around the world.
Comet Lemmon (C/2025 A6) as imaged using a Seestar S30 smart telescope from New Brunswick, Canada, by Stéphane Picard at Cliff Valley Astronomy on October 4, 2025.
Stéphane Picard, Cliff Valley Astronomy (used with permission)
Key Facts
Comets are visible in the northwest (Lemmon) and southwest (SWAN) about 90 minutes after sunset. SWAN will be visible below the stars of the Summer Triangle while Lemmon will move faster across the sky below the Big Dipper.
The easiest way to find comets in the night sky is to use the finder maps at In-The-Sky.com or stargazing apps like Sky Guide, Stellarium and SkySafari.
With Comet Lemmon shining at magnitude +4.9 and Comet SWAN slightly dimmer at magnitude +5.9, those at magnitude Dark Sky Place or somewhere that looks dark in a light pollution map he may be able to see them with the naked eye. However, you will most likely require 8×42 or 10×50 binoculars to see them.
The Virtual Telescope Project will live image streaming of both comets from 17:30 UTC (1:30 p.m. EDT) on Monday, October 20, using robotic telescopes installed in Manciano, Italy.
Sky watchers who want to see one or both of Comet Lemmon and Comet SWAN should try this week. Besides the brightness of the comets being famously difficult to predict (both could undergo an outburst and either brighten or fade at any time), moonlight will begin to interfere with observations starting next weekend, making next week the best time to see the comets.
The Orionid meteor shower peaks on October 21-22, producing about 20 meteors per hour under clear, dark skies. They will likely be best seen after midnight until dawn, when the constellation Orion rises high in the southeast.
Comet Lemmon can be seen before dawn on October 20 — the best time will be 6:00 AM. EDT.
Stellarium
When and where to see comets
The best time to spot Comet Lemmon and Comet SWAN on Monday, October 20 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 – Lemon in the northwest, SWAN in the southwest. For New York, where sunset is at 6:05 p.m. EDT, the ideal time for evening viewing is 7:35-8:05 p.m. EDT.
Comet Lemmon can also be seen before dawn — but not for long. Look during a 15-minute window starting about 75 minutes before sunrise. At sunrise at 7:13 am. EDT in New York, the best time will be around 6:00-6:15 AM. EDT — though earlier observations may also reveal the comet rising in the northeast.
The best time to see Comet Lemmon on October 20 will be 90 minutes after sunset.
Stellarium
How to find Comet Lemmon
Distance from the Sun: 64.1 million miles (103.2 million kilometers)
Distance from Earth: 55.5 million miles (89.3 million kilometers)
Before sunrise, the comet will be in the northeast. The Ursa Major handle – which will point down towards the horizon – can be used to find it. Trace the stars of Ursa Major’s handle in an arc, or banana shape, to descend in a curve on the northeastern horizon. From New York, the comet will be about 6 degrees high at 6:00 AM. EDT, and although it will climb higher as dawn approaches, after about 15 minutes, the sky will be white. Venus rises at about the same time.
After sunset, look for Comet Lemmon two-thirds of the way along a line between Alkaid—the bright star at the end of Ursa Major’s handle—and the bright star Arcturus farther west. Its height above the horizon varies by location, but from New York it will appear about 17 degrees above the northwest horizon at 7:35 p.m. EDT — about the width of four outstretched fingers held at arm’s length — and will gradually sink as twilight deepens.
The best time to see Comet SWAN on October 20 will be 90 minutes after sunset.
Stellarium
How to find Comet Swan
Distance from the Sun: 91.7 million miles (147.6 million kilometers)
Distance from Earth: 24.4 million miles (39.2 million kilometers)
The blue-green comet SWAN will be visible with binoculars on Monday, October 20, low in the southwest after sunset. Cygnus will be in the constellation Sagittarius, above the famous constellation “Tea”, but also below the bright star Altair in the Summer Triangle. It lies in front of the dense star fields of our Milky Way, which will be visible behind the comet with binoculars.
The best time to look for Comet SWAN will be a 30-minute window starting about 90 minutes after sunset where you are. For New York City, sunset is 6:05 PM. EDT, so the ideal viewing time would be from 7:35 to 8:05 p.m. EDT (although it will be visible until approximately 11:00 p.m. EDT). The comet’s height above the horizon will vary depending on your location, but from New York, it will be about 34 degrees up as it becomes visible.
Check out my feed each day this month for a daily “comet tracker” with finder charts and tips for viewing Comet Lemmon and Comet SWAN from mid-northern latitudes. Read also How to photograph green comets, The best star apps for finding comets and 25 Dark Sky Parks in the US to See Comets.
