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The green comets visible in the night sky are now at their minimum distance from Earth, so they should be at their brightest in the night sky. Comet Lemmon (also called C/2025 A6) and Comet SWAN (C/2025 R2) are the first comets visible in binoculars since Comet Tsuchinshan-ATLAS in October 2024. Both are visible after sunset from the Northern Hemisphere, but Tuesday, Oct. 21, is the last chance to also see Lemmon before sunrise.
The best time to spot Comet Lemmon and Comet SWAN on Tuesday, Oct. 21, 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 6:03 p.m. EDT, the ideal time for evening viewing is 7:33-8:03 p.m. EDT.
Comet Lemmon can also be seen before dawn -- though not after Tuesday. With sunrise at 7:15 a.m. EDT in New York, the best time will be 6:00-6:15 a.m. EDT.
Distance from the sun: 62.8 million miles (101.1 million kilometers)
Distance from Earth: 55.4 million miles (89.2 million kilometers)
Before sunrise, the comet will be in the northeast. The Big Dipper's handle -- which will point down toward the horizon -- can be used to find it. Trace the stars of the Big Dipper's handle in an arc, or banana-shape, to go in a curve down to the north-east horizon. From New York, the comet will stand about 6 degrees high at 6:00 a.m. EDT, and though it will climb higher as dawn approaches, after about 15 minutes, the sky will be bleached. Venus rises at about the same time.
After sunset on Tuesday, Oct. 21, look for Comet Lemmon above-right of bright star Arcturus, low on the northwest horizon. Its height above the horizon varies by location, but from New York, the comet will appear about 18 degrees above the northwest horizon at 7:33 p.m. EDT -- roughly the width of four outstretched fingers held at arm's length -- and will gradually sink as twilight deepens.
Distance from the sun: 93.3 million miles (150.2 million kilometers)
Distance from Earth: 24.5 million miles (39.5 million kilometers)
Bluish-green Comet SWAN will glow in binoculars low in the south-west after sunset, now in Aquila beneath the bright star Altair of the Summer Triangle. It lies in front of the Milky Way's dense star fields, which will be visible behind the comet in binoculars. The comet's height above the horizon will vary depending on your location, but from New York at 7:33 p.m. EDT, it will be around 38 degrees up as it becomes visible.