What do we know about the second object to visit us from another stellar system? Detailed Hubble images have given us plenty to consider!
Extrasolar Guests Among Us
Artist’s interpretation of interstellar asteroid 1I/’Oumuamua. [M. Kornmesser/ESO]When asteroid 1I/‘Oumuamua tore through our solar system last year, it was a one-of-a-kind event: the first time we had observed an object from another stellar system pass through our own. But nature likes to keep us on our toes — and it wasn’t long before the next interstellar object paid us a visit.
In October of 2019, comet 2I/Borisov was first spotted. The body swung through perihelion — the point closest to the Sun — in December and then sped along on its way back out through our solar system. It’s expected to reach the distance of Jupiter in July of 2020, and the distance of Saturn by March of 2021.
Apples and Oranges, Asteroids and Comets
Our two interstellar visitors thus far, however, are surprisingly dissimilar. Unlike ‘Oumuamua, Borisov doesn’t have an obviously elongated, tumbling shape. And though observations of ‘Oumuamua showed it to be entirely inactive, Borisov has the appearance of a typical solar system comet: it has a prominent coma — ...