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.

A pair of once-in-a-lifetime comets are 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),

Lemmon, which is a rare green comet, can be seen with the naked eye on Oct. 21, according to the Royal Astronomical Society, with peak visibility near Halloween. SWAN may be visible using binoculars or a telescope, according to Starwalk, a real-time astronomical app for stargazing.

Astronomer Gianluca Masi captured spectacular footage of a glowing meteor trail wrapping around the colossal tail of Comet Lemmon on Oct. 24, as the wandering solar system body approached the constellation Serpens Caput in Earth's sky.

The interstellar object 3I/ATLAS has gathered significant scientific attention, and soon it will reach its closest point to the sun.

The comets are visible in the northwest (Lemmon) and southwest (SWAN) about 90 minutes after sunset. Lemmon is moving quickly across the sky west of the Big Dipper, close to bright star Arcturus, while SWAN is beneath the three bright stars that comprise the Summer Triangle. At magntitude +4.4, Lemmon is by far the brighter and easiest to see.

Could a ‘Trojan Horse’ from space be headed our way? Harvard scientist Avi Loeb warns 3I/ATLAS might be more than the average a comet.

A newly discovered comet is about to make its closest pass to Earth on Tuesday night. It should be visible over the Bay Area before it disappears — and won’t be seen again for more than a thousand years.

Harvard Professor Avi Loeb discusses the mystery surrounding the 31/ATLAS comet and explains his argument that it has a 40% chance of being alien technology.