Scientists say interstellar comet has led a very cold existence

Enlarge / An image of interstellar comet 2I/Borisov, (credit: NASA)

Comets are essentially time capsules. Most formed during the early days of our Solar System, amid the disk of dust and gas around the Sun. The majority of this dust and gas coalesced into planets, but some of the leftovers-especially toward the outer edge of the disk-wound up in comets.

Because comets spend much of their time in cold expanses far from the Sun, their interiors are relatively well preserved. Thus most comets offer scientists an unprecedented view of what conditions were like in the earliest days of the Solar System before planets formed.

To date, astronomers have studied hundreds of comets in our Solar System to understand its origin. But now, they've been able to look at the interior of an interstellar comet for the first time. In two new papers published in Nature Astronomy, scientists trained two of their most powerful observatories on 2I/Borisov, the first confirmed comet to enter our Solar System from elsewhere.

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