Late last year, our solar system received an unexpected visitor from interstellar space: The asteroid ‘Oumuamua that was discovered suddenly in October and then just as quickly disappeared, passing briefly through our solar system on the way to somewhere else. But now we have a better chance to study a visitor from beyond our solar system.
According to scientists from the Côte d'Azur Observatory and São Paulo State University, there’s at least one interstellar asteroid already here. They , and unlike ‘Oumuamua, this asteroid is here to stay.
Asteroid 2015 BZ509 was discovered a few years ago by the Pan-STARRS sky survey, the same one that discovered ‘Oumuamua last year. This new asteroid, 2015 BZ509, is a pretty strange one because it orbits in retrograde—in the opposite direction as pretty much everything else in the solar system.
The researchers mapped the asteroid’s orbit and ran a computer simulation showing what the asteroid was up to in the past. The simulation showed that 2015 BZ509 was orbiting out by Jupiter backwards since the early years of our solar system, which means it is almost certainly not native.
This new discovery provides a great opportunity for scientists to study an interstellar asteroid, because 2015 BZ509 isn’t going anywhere. It also suggests that there could be plenty of interstellar asteroids lurking elsewhere in our solar system waiting to be discovered and studied. Once we find those we could start to learn a great deal about the universe beyond our own planetary neighborhood.