Weird backwards asteroid may be an interstellar interloper

By John Wenz

There’s an alien living among us. An asteroid out near Jupiter has been behaving strangely, and astronomers now think that may be because it didn’t come from our solar system.
Originally discovered in 2015, asteroid 2015 BZ509 orbits in the opposite direction of all the planets, including Jupiter, whose orbit the asteroid crosses periodically. A constant push-and-pull from those near passes with the gas giant has stabilized the asteroid’s orbit over billions of years.
It likely arrived here early in our solar system’s history from …