The second interstellar comet detected in our Solar System now has an official name. Meet 2I/Borisov, the latest object to zoom into our cosmic neighborhood from somewhere very far away.
The object formerly known as C/2019 Q4 was given its name on Tuesday by the International Astronomical Union, the organization that officially names just about anything in the Universe that isn’t on Earth. The 2I refers to the fact that researchers are now confident that this is the second interstellar object ever discovered in our Solar System.
Researchers have been tracking the object since it was discovered on August 30th by an amateur astronomer in Crimea named Gennady Borisov. And that’s where the second part of this object’s name comes in — the object Borisov was tracking through his homemade 0.65 meter telescope looked like a comet, with a distinctive haze, or “coma.” Comets, unlike asteroids, moons, or other space features, are usually named after their discoverer, which makes this comet’s full designation 2I/Borisov.
The only other known interstellar object is named 1I/’Oumuamua, which was initially thought to be a comet, then an asteroid when it was first discovered in 2017. Asteroids are typically named by the people who discover them, instead of after them, so the team who found it in Hawaii decided to name it ‘Oumuamua, a Hawaiian name meaning “a messenger from afar arriving first.” Later observations indicated that it might be a comet after all, but by then, the name had stuck.
2I/Borisov is more assuredly a comet, with a short tail already visible to astronomers. The comet, estimated to be a few kilometers across, will make its closest approach to the Sun on December 7th, 2019, before it starts heading back out of the Solar System. That gives astronomers a generous amount of time to track this interstellar visitor, and hopefully learn more about where it’s from, and what it’s made of, before it disappears for good.