• LHS 1140 b, an exoplanet orbiting a low-mass red dwarf star roughly one-fifth the size of the Sun, has captivated scientists due to it being one of the closest exoplanets to the solar system that lies within its star’s habitable zone. 

• Exoplanets found in this ‘Goldilocks Zone’ have temperatures that would allow water to exist on them in liquid form, a crucial element for life as we know it on Earth.

• The distance Earth orbits the Sun is just right for water to remain a liquid. This distance from the Sun is called the habitable zone, or the Goldilocks Zone. 

• Analysis shows LHS 1140 b could be a Super-Earth ice or water world.

• Current models indicate that if LHS 1140 b has an Earth-like atmosphere, it would be a snowball planet with a bull’s-eye ocean about 4,000 kilometers in diameter, equivalent to half the surface area of the Atlantic Ocean.

What is Super-Earth?

• Super-Earth is more massive than Earth yet lighter than ice giants like Neptune and Uranus, and can be made of gas, rock or a combination of both. It is between twice the size of Earth and up to 10 times its mass.

• Super-Earth is a reference only to an exoplanet’s size — larger than Earth and smaller than Neptune — but not suggesting they are necessarily similar to our home planet. 

• The true nature of these planets remains shrouded in uncertainty because we have nothing like them in our own solar system, and yet, they are common among planets found so far in our galaxy.

LHS 1140 b in the constellation Cetus

• The exoplanet, called LHS 1140 b, was first discovered in 2017.

• One of the critical questions about LHS 1140 b was whether it is a mini-Neptune type exoplanet or a super-Earth.

• Analysis by a team of scientists based on data from the James Webb Space Telescope (JWST) strongly excluded the mini-Neptune scenario, with evidence suggesting the exoplanet LHS 1140 b is a Super-Earth that may even have a nitrogen-rich atmosphere like that of the Earth. 

• The planet, located about 48 light-years away in the constellation Cetus, emerges as one of the most promising habitable zone exoplanet candidates known, potentially harboring an atmosphere and even a liquid water ocean.

• It could be an “eyeball” planet with an iris-like ocean surrounded by a sea of solid ice.

• 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, said the team of scientists.

• Estimates based on all accumulated data reveal that LHS 1140 b is less dense than expected for a rocky planet with an Earth-like composition, suggesting that 10 to 20 per cent of its mass may be composed of water. 

• This discovery points to LHS 1140 b being a compelling candidate water world, likely resembling a snowball or ice planet with a potential liquid ocean at the sub-stellar point, or the area of the planet’s surface that would always be facing the system’s host star due to the planet’s synchronous rotation (much like the Earth’s moon).

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