An interstellar object is a comet or asteroid that formed around another star and is passing through our solar system on an unbound, hyperbolic trajectory. The first confirmed was 'Oumuamua in 2017, followed by comet 2I/Borisov and, more recently, 3I/ATLAS. Each is a rare physical sample of material from another planetary system, and surveys like the Vera Rubin Observatory are expected to find many more.