ByJamie Carter,
Senior Contributor.
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.
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).
