What better to draw you off your sofa and out into the dark fall night than the chance to spot a pair of comets that will never return to Earth in our lifetimes?
These heavenly bodies, named Lemmon and SWAN, are non-periodic comets, meaning they are unlikely to pass through our solar system for many thousands of years, if ever. But this week, they will be flying through our skies.
The twin comets will be visible throughout this week. Lemmon peaked in brightness yesterday (October 21, 2025) and SWAN the day before (October 20, 2025).
Read More: When Was Halley’s Comet Last Seen and Will It Ever Return?
How To Spot Comet Lemmon
Comet Lemmon (C/2025 A4), passing around 56 million miles (90 million kilometers) from Earth, was first spotted in January. You can spot it this week using a small telescope or a pair of binoculars.
Observers lucky enough to have a view of a very dark sky may even be able to see it with the naked eye. It will appear after sunset in the western sky. It will move steadily northward throughout the week.
“As the sky darkens, the comet will first of all be moving, over a matter of days, past the bright star Arcturus, and then further round towards the southwest, beneath the stars of the Summer Triangle,” said Robert Massey, an astronomer with the Royal Astronomical Society, in a press release.
It will look “fairly bright” and “fuzzy”, said Massey. The comet will likely not appear again for 1,300 years, so this week is your last chance unless you have access to some sophisticated cryogenic technology.
How To Spot Comet SWAN
Comet SWAN (C/2025 R2) was first seen on September 10, 2025. It will pass closer than Lemmon, going as close as 24 million miles to Earth. To see it, you’ll have to get up early.
Before dawn, it should appear in the eastern sky. Although it comes closer to Earth than Lemmon, SWAN will appear dimmer, but it will still be easy to spot using a pair of binoculars.
To find SWAN, look again for the Summer Triangle. The comet should appear midway between one of these stars — Altair, in the constellation of Aquila — and the horizon. It won’t be back for 20,000 years — even the best cryogenics probably won’t help you see SWAN again.
Read More: A Comet Could’ve Caused Rapid Climate Shift Around 12,800 Years Ago
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