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Comet 2I/Borisov Came From Another Star, But It Looks Oddly Familiar The comet, 2I/Borisov, looks surprisingly like comets closer to home. It's a sign that the processes that formed the sun and planets are at work elsewhere in the universe.

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< A Comet From Another Star Hints That Our Solar System Isn't One-Of-A-Kind

A Comet From Another Star Hints That Our Solar System Isn't One-Of-A-Kind

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AILSA CHANG, HOST:

And now some news from outside the solar system, literally. A comet from another star is drawing near our sun. NPR's Geoff Brumfiel reports on this interstellar visitor.

GEOFF BRUMFIEL, BYLINE: The comet is known as 2I/Borisov, or just Borisov for short. It was discovered back in August, and quickly, astronomers realized it was special. Most comets we see go around the sun. Borisov is coming in from deep space. Ye Quanzhi of the University of Maryland is one of many astronomers trying to figure out where the heck it came from.

YE QUANZHI: We know this is definitely not from the solar system, and the universe is big. So we can only speculate.

BRUMFIEL: Do you have a hunch?

QUANZHI: Me? No (laughter). Not yet.

BRUMFIEL: Ye and his colleagues have been looking at all the photos of the comet, trying to trace its trajectory and thus work out which star it might have come from. Even if they can, it would only tell them the last place Borisov visited. There's no way to know where this wanderer's journey started. It could have formed around another star many millions or even billions of years ago. But for something that's traveled potentially eons across the galaxy, Borisov actually looks pretty familiar.

QUANZHI: So far, comet Borisov seems just like some of the solar system comets. That means there's something universal in the universe.

BRUMFIEL: The same cosmic forces that formed our solar system and all the comets that go around our sun seem to be at work elsewhere. Of course, there's no way to know if those forces have also made other Earths or life or little green people with telescopes of their own. But Borisov is one data point to suggest that our solar system is maybe not alone. Borisov will swing by the sun on December 8. After that, it'll shoot back out into the icy void, onto the next star.

QUANZHI: We're pretty sure that we are never going to see it again. I just find it pretty sad (laughter).

BRUMFIEL: Why do you find it sad?

QUANZHI: Oh, it's gone, you know? It's just like, you miss someone, and you're pretty sure you're not going to see him or her again.

BRUMFIEL: But even though our paths crossed only briefly, it seems that astronomers have found something in common with comet Borisov.

Geoff Brumfiel, NPR News.

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