ISO: A home for a stray space rock. Astronomers are tracking the motions of stars to figure out which one sent an alien asteroid speeding past Earth in October — but they may never find the rock’s true origins.
Officially named ‘Oumuamua, the asteroid was spotted by the Pan-STARRS 1 telescope in Hawaii on October 18 (SN: 11/25/17, p. 14). Its inbound speed of about 25.5 kilometers per second and its slingshot route around the sun pegged it as the first interstellar vagabond ever seen.