With thousands of exoplanets discovered to date, it’s no wonder that we regularly come across “Earth-like worlds” around distant stars. But let’s face it: while it’s exciting that there are planets out there that may be able to harbour life, they are so far away that we will not be able to visit them anytime soon.
So wouldn’t it be amazing if we discovered a planet just like the Earth – in our own neighbourhood? Well, a new study led by some of my colleagues at Queen Mary University of London has finally done just that. Proxima Centauri – a “red dwarf” star that’s some 14% the size of the sun and around half the temperature – is the closest star to our solar system at 4.24 light years away. Until now, we weren’t sure if it had any planets in orbit, but the new study, published in Nature, reports the discovery of a potentially habitable world that we may actually be able to send tiny robots to in the next few decades.
The team behind the discovery is called Pale Red Dot – an observational campaign of the High Accuracy Radial velocity Planet Searcher (HARPS), an instrument on the European Southern Observatory’s 3.6-metre La Silla telescope in Chile’s Atacama Desert. It measured the spectra of light from Proxima, essentially the fingerprints that reveal what the star is made of, and looked for changes in the frequency of those lines. Small shifts in this starlight can be used to work out tiny movements of the star in response to an orbiting planet’s gravitational pull.
Y. Beletsky (LCO)/ESO/ESA/NASA/M. Zamani
Pale Red Dot’s measurements were made each night for around three months at the beginning of 2016. And the results revealed the tell-tale signature of a planet, now labelled “Proxima b” as per naming conventions.