This week, Earth gets a front-row seat to one of the solar system’s oldest relics. On October 21, Comet C/2025 A6 (Lemmon) will pass closest to Earth—its first and only appearance for more than a thousand years.

“Comets are very common, but Comet Lemmon is definitely the best comet to view from Earth this year,” says Rhonda Stroud , the director of the Center for Meteorite Studies at Arizona State University in Tempe, Arizona.

Where did this comet come from—and how can you spot it in the night sky? Here’s what to know before it passes.

Where did the comet come from?

Space isn’t completely empty. Within our solar neighborhood, it’s sprinkled with ice and dust particles that can be found between planets, stars, and even galaxies. Comets and asteroids are evidence of the ice and d

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