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[Music throughout] Last summer, an amateur astronomer discovered

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the first interstellar comet zipping through our solar system – 2I/Borisov.

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It was clear from its path that the comet would dim from view within months,

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so scientists were quick to turn their telescopes towards the alien comet for a view.

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Among them was an international team led by NASA Goddard.

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They used the ALMA telescope array in northern Chile to probe 2I/Borisov while it was close by.

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Inside the halo of gas around the comet, they detected something peculiar.

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2I/Borisov was releasing a higher concentration of carbon monoxide

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than any comet observed at a similar distance from the Sun.

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NASA’s Hubble Space Telescope later confirmed this, too.

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Scientists wondered – Could this be our first glimpse of the chemistry of another planetary system?

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Or are we learning that there’s more chemical diversity among comets than we knew of?

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Carbon monoxide is one of the most abundant molecules in space.

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Scientists expect to see it inside all comets; yet, there’s a huge variation – which is puzzling

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Regardless, 2I/Borisov is off the charts.

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To preserve its carbon monoxide, the comet likely formed

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very far away from its star in one of the coldest environments known.

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In our solar system, this would have been in the vicinity of Neptune.

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When comets were forming, temperatures there could’ve reached -420 degrees Fahrenheit.

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Scientists think that gravitational disturbances from young, jostling planets may have thrown

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2I/Borisov out of its home star system and onto a cold, lonely voyage.

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Our solar system is tiny compared to the distances between star systems.

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It’s incredibly rare for an interstellar comet to pass within observable range.

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However, big, sophisticated telescopes are coming online,