A few months ago, scientists predicted that it would take two more years until we found another habitable planet somewhere out there. Well, one team of astronomers may have just shattered that prediction, because the planet they just found looks very promising and very Earth-like.
Working with publicly available data from the High Accuracy Radial velocity Planet Searcher (HARPS) in Chile, a team of researchers at the University of Hertfordshire Centre for Astrophysics Research focused on three different exoplanets, all super Earths (meaning their mass is greater than our own planet), surrounding HD 40307, an orange dwarf star about 43 light-years away from Earth.
But of those three the last one, HD 40307 g, is proving to be the most interesting. It's orbiting in the star's habitable zone, which means it could have liquid water, but it's also orbiting far enough away to avoid tidal lock. This means that, unlike cosmic bodies like our moon, one side of the planet isn't always hot while the other is always cold. This means it doesn't have the extreme weather conditions that other tidally locked planets have (searing heat on one side, freezing cold and darkness on the other), and makes it even more like Earth.
But while the Hertfordshire team's findings are thrilling, they aren't yet confirmed. At this point, HD 40307 g is still just a candidate as a habitable world. And to prove that it is in fact a system that can support life, we'll likely have to do more than stand in an observatory and look up.
"A more detailed characterization of this candidate is very unlikely using ground based studies because it is very unlikely [sic] to transit the star, and a direct imaging mission seems the most promising way of learning more about its possible atmosphere and life-hosting capabilities," the team said in a paper set to be published in Astronomy & Astrophysics.
If it turns out that the team is right, HD 40307 g is a huge discovery, not just because it could support life similar to Earth's, but because it demonstrates that Earth-like planets don't necessarily have to form in Earth-like solar systems.
"The planetary system around HD 40307 has an architecture radically different from that of the solar system... which indicates that a wide variety of formation histories might allow the emergence of roughly Earth-mass objects in the habitable zones of stars," the team said.