A telescope’s angular resolution is its ability to distinguish small details of a distant object. The Hubble Space telescope, for example, has an angular resolution of about 100 milliarcseconds.
That’s good but by no means the best. In fact, the telescopes with the highest angular resolutions are interferometric radio telescopes, made up of several dishes spread over thousands of kilometres.
Known as very long baseline interferometers (VLBIs), the biggest boast an angular resolution some two orders of magnitude better than Hubble.
So what to point them at? Today, Hayden Rampadarath and pals at the International Centre for Radio Astronomy Research at Curtin University in Australia say they’ve pointed their interferometric radio telescope at Gliese 581, a red dwarf star some 20 light years from here.
What makes Gliese 581 interesting is its planets, which include two superEarths that probably sit on the edge of their habitable zone.
That makes them good candidates for life. And if this life is anything like our own, it may already be broadcasting at radio frequencies that we can tune in to.
Although VLBI has extraordinary angular resolution, it has never been used to look for signs of extraterrestrial intelligence. So this is an important proof-of-principle step.