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 C/2025 A6 (Lemmon) is this year’s brightest comet visible from Earth—an icy relic from the solar system’s origins that won’t return until the next millennium.

This long-duration comet will make its closest approach to Earth this fall, before disappearing into the outer solar system for another 1,000 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.

Comet C/2025 A6 (Lemmon) will pass through the neck of the great celestial serpent represented by the constellation Serpens Caput on the nights of Oct. 26-27.

A pair of once-in-a-lifetime comets is rocketing through our skies right now, and it's a rare treat because they won't be back for hundreds of years. The comets, C/2025 A6 (Lemmon) and C/2025 R2 (SWAN),

Comet C/2025 A6 — also known as Lemmon — will make its closest approach to Earth on Tuesday night, Oct. 21, and will continue to brighten as it travels toward the sun. For the next several weeks, should the comet remain intact, it will remain visible in the evening sky, even detectable with the unaided eye in darker skies.