Nearby exoplanet could be first known ocean world: Webb telescope

PARIS: A planet relatively close to Earth could be the first ever detected with a potentially life-sustaining liquid ocean outside our Solar System, according to scientists using the James Webb space telescope.

More than 5,000 planets have been discovered outside of the Solar System so far, but only a handful are in what is called the “Goldilocks zone” -- neither too hot or too cold -- that could host liquid water, a key ingredient for life.

The exoplanet LHS 1140 b is one of the few in this habitable zone, and has been thoroughly scrutinised since it was first discovered in 2017.

It sits 48 light years from Earth, which equates to more than 450 trillion kilometres -- relatively close in the vast distances of space. The exoplanet had been thought to be a small gas giant called a “mini-Neptune” with an atmosphere too thick with hydrogen and helium to support alien life.

However, new observations from the Webb telescope have confirmed that the exoplanet is in fact a rocky “super-Earth”. It is 1.7 times bigger than Earth, but has 5.6 times its mass, according to a study published late Wednesday in The Astrophysical Journal Letters. The Webb telescope was able to analyse the planet´s atmosphere as it passed in front of its star.

There were no signs of hydrogen or helium, which ruled out that the planet was a mini-Neptune. The density of the planet indicates that it “actually has large quantities of water,” study co-author Martin Turbet of France´s CNRS scientific research centre told AFP.