WOULD WE SPOT AN ALIEN PROBE AT ALL?
An alien spacecraft could easily visit our Solar System without us ever noticing. Astronomers estimate at least one interstellar asteroid similar to `Oumuamua passes through our Solar System every year, but it is hard to recognise a faint, fast pinprick of light in the vastness of space. Indeed, `Oumuamua was already on its way out of the system by the time it was spotted.
The only reason we now have any chance of spotting interstellar objects is thanks to new automated surveys like PAN-STARRS, the Catalina sky survey and the ATLAS survey, which scour the sky for moving objects.
Horner says: “We’re only just reaching the technological level to have a good chance of catching these things.” If `Oumuamua had come along just a fortnight earlier or later, he believes PAN-STARRS probably would have missed it, due to it being too far from Earth or too close to the Sun to see.
Future technology will expand our abilities to spot and study these far-flung visitors. The much more powerful Large Synoptic Survey Telescope (LSST) being built in Chile, UCLA’S Jewitt says, should detect interstellar objects “by the bucket-load”.
Identifying and carefully studying these objects will allow us to build up a database of their properties. If an alien-built interstellar visitor does arrive, we’ll have a better chance of recognising its true nature.
Then the real fun will begin. LAUREN FUGE is a freelance science writer based in Adelaide, Australia.