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[Music throughout] [Hubble Space Telescope images]

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2I/Borisov is the first active interstellar comet scientists have seen.

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As the comet approached the Sun, it shed millions of gallons of water. [Swift images]

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NASA’s Neil Gehrels Swift Observatory measured how much. 

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Swift made several observations during the comet’s first and only trip through the solar system.

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[Illustration] [Approximately 0.5 miles across, 0.74km]

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It detected the signal of both water and dust given off by the small comet.

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As Borisov neared the Sun, its water production rose similarly to solar system comets.

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When it was closest to the Sun, the comet lost enough water to fill a bathtub in about 10 seconds.

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At that point, at least 55% of the surface was releasing water, which is about 10 times more than solar system comets.

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[Graph of water loss]

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As Borisov moved away from the Sun, its water production rate fell off faster than any other comet yet observed.

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During its trip, Borisov lost a total of around 60 million gallons of water.

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Swift measurements show that material coming off of Borisov is similar to solar system comets.

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Thanks to Swift, astronomers have measured the water production of a comet from a planetary system beyond our own.

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[Explore: Solar system and beyond]

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[NASA]