The duo reaches peak brightness Monday, Oct. 20, and Tuesday, 21, with viewing continuing through late October. Both are best seen from the Northern Hemisphere.
Comet Lemmon (C/2025 A6) should be the easier catch. Look about 90 minutes after sunset or before dawn toward the northwestern sky, near the Big Dipper.
Expect a faint, fuzzy, blue‑green glow rather than a sharp point of light. Binoculars will help it stand out as a small, greenish ball. Lemmon follows a 1,350‑year orbit and was discovered in January 2025.
Comet SWAN (C/2025 R2) is dimmer but nearby in cosmic terms. It makes its closest pass on Monday, and will likely fade as it moves away from the Sun and Earth.
Try the southwestern sky after sunset. You will almost certainly need binoculars to see it well. SWAN was discovered in September 2025 and takes more than 22,000 years to loop the Sun.
For the best view, escape city lights, find a wide, unobstructed horizon, and recline so you can scan a large swath of sky. Give your eyes 20 to 30 minutes to adapt to the dark. Most binoculars, such as 8x42 or 10x50, are ideal for spotting these small, diffuse glows. No telescope is required.
Comet brightness is notoriously fickle. While forecasts suggest both could flirt with naked‑eye visibility in very dark locations, they can brighten or fade unexpectedly. If clouds spoil one night, try again on the nights before or after the peak.
The Orionids meteor showers will also be on display this week. Ideal viewing arrives late Monday evening, Oct. 20, through the predawn hours of Tuesday, Oct. 21, thanks to a new moon that leaves the sky dark. But there will be other opportunities to see it. The shower is active now and runs into Friday, Nov. 7.
The Orionids come from Earth plowing through dust shed by Halley's Comet.
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