Hands up who can’t wait until we find concrete proof of extraterrestrial life?
The idea that there are other lifeforms out there, hopefully fully-fledged civilisations, is one that has obsessed generations of scientists, writers and alien enthusiasts.
Now, a team of astronomers have discovered the ‘best bet yet’ for a planet capable of hosting life, a mere 48 light-years away in the constellation Cetus.
Known as LHS 1140 b (heaven forbid we give exoplanets memorable, accessible names), the distant world is 1.7 times the size of Earth and, importantly, could be covered in water – whether icy or liquid.
Water is generally seen as an essential element for the formation of life, so the idea that LHS 1140 b is a rocky planet with at least some liquid water covering it is hugely exciting.
Current analysis, conducted using a range of data including information gathered by the James Webb Space Telescope (JWST), suggests that 10 to 20% of its mass may be composed of water.
In addition, its location in the ‘Goldilocks Zone’ around its star means it is neither too hot nor too cold for liquid water (and, perhaps, life). This means the team believes at least some it is in the form of an ocean, with a surface temperature of a comfortable 20C.
But the excitement doesn’t stop there.
The data also suggests LHS 1140 b has an atmosphere, one that may be rich in nitrogen, similar to Earth’s. The combination of atmosphere, water and living in the Goldilocks Zone has led the team to believe the planet is mostly covered in ice – a snowball planet, as Earth once was.
However, they also predict there could be a liquid ocean in the middle, around half the size of the Atlantic, on the side facing away from its star, creating the appearance of a bull’s eye, or eyeball, floating in space.
Charles Cadieux, lead author of the paper available on the preprint site ArXiv, said: ‘Of all currently known temperate exoplanets, LHS 1140 b could well be our best bet to one day indirectly confirm liquid water on the surface of an alien world beyond our solar system.
‘This would be a major milestone in the search for potentially habitable exoplanets.’
Ryan MacDonald, from the University of Michigan, added: ‘This is the first time we have ever seen a hint of an atmosphere on a habitable zone rocky or ice-rich exoplanet. Detecting atmospheres on small, rocky worlds is a major goal from JWST, but these signals are much harder to see than for giant planet atmospheres.
‘LHS 1140 b is one of the best small exoplanets in the habitable zone capable of supporting a thick atmosphere, and we might just have found evidence of air on this world.’
In may, astronomers found evidence that rocky exoplanet 55 Cancri e may also have an atmosphere, but is too close to its star to be habitable, taking just one day to travel all the way around it.
