By 3 News online staff
An exoplanet discovered in 2010 has been rated the best candidate for potential human habitation, should we manage to leave Earth at some point in the future.
There are problems, however – it's 20 light years away, could be twice as large as Earth, and some astronomers doubt it even exists.
The Planetary Habitability Laboratory of the University of Peurto Rico analysed known exoplanets for their similarity to Earth in size, orbit and likely surface conditions, and have named Gliese 581g our best bet.
According to new research, the planet sits comfortably in what astronomers call a "Goldilocks zone" orbit – this means it is just the right distance from its star to receive a similar amount of light and energy as Earth does. It also appears to have a circular orbit, rather than an elliptical one, meaning it stays a consistent distance from the star.
It's estimated to have a diameter around 1.5 times that of Earth and a mass of 2.2 Earths, meaning anyone standing on it would be significantly heavier than they were on Earth.
Despite this, Gliese 581g has been given an Earthlike-rating of 0.92, where exactly like Earth is 1.0, and completely unlike Earth is 0.0.
Mars – our closest neighbour, and likely next target for human exploration – only has a rating of 0.66.
But some astronomers say the evidence for Gliese 581g's existence is weak, and since we currently have no way to get to the moon – let alone another solar system – don't get your hopes up.
There are now over 800 known exoplanets.