‘Alien’ heads wrong way through one-way space

An asteroid from another star system has been discovered sharing Jupiter’s orbit.

Through a telescope the asteroid looks like every other in the solar system save for one crucial difference – it is travelling in the wrong direction. It is the first time an interstellar space rock has been discovered permanently residing in the Solar System.

The first clue that the 1.8-mile-wide rock – code-named 2015 BZ509 – was not native was its “retrograde” orbit, travelling in the opposite direction to all the planets and almost every other object in our system, according to the journal Monthly Notices of the Royal Astronomical Society.