Chris Lintott

In October 2017, the Pan-STARRS telescope in Hawaii spotted an object moving too fast to belong to the solar system. It was 1I/ʻOumuamua, the first interstellar visitor ever recorded by astronomers. Since then, two more have joined it: comet 2I/Borisov and object 3I/ATLAS.

When telescopes spotted the interstellar object 1I/‘Oumuamua in 2017, astronomers touched for the first time matter born around an alien star. But an uneasy question immediately arose: what if some of these visitors are not strangers at all, but ghosts from our own past?

Remember the sensational comet 1I/‘Oumuamua — the first object to come to us from another star? Its hyperbolic trajectory left no doubt: it was a wanderer from the interstellar void. But astronomers wondered: could some of these visitors not be strangers at all, but our own, escaped from the Solar System millions of years ago?