The TOI-270 d is a sub-Neptune distant exoplanet.
Astronomers using the James Webb Space Telescope (JWST) have found hints of a distant planet that could be entirely covered in a deep ocean.
The planet, known as TOI-270 d, is located 70 light-years away and is twice the size of Earth.
Observations of the planet's atmosphere revealed water vapour, methane, and carbon dioxide, which is consistent with a water world. However, there is disagreement among scientists about the details.
A team from the University of Cambridge believes the planet could have a vast ocean spanning its entire surface. They base this on the lack of ammonia in the atmosphere, which would be absorbed by a large ocean.
"One interpretation is that this is a so-called 'hycean' world-with a water ocean under a hydrogen-rich atmosphere," said Proffessor Nikku Madhusudhan, who led the analysis.
On the other hand, a Canadian team argues that TOI-270 d might be too hot for liquid water, with temperatures reaching 4,000 degrees Celsius. They believe the planet could have a rocky surface with a thick atmosphere of hydrogen and water vapour.
Scientists believe there might be an ocean on TOI-270 d because they haven't detected ammonia in its atmosphere. According to basic chemistry, ammonia should be present in a hydrogen-rich atmosphere, but it's not there. This absence suggests that if there's an ocean below, it could have absorbed the ammonia from the atmosphere.
The James Webb Space Telescope (JWST) is a space telescope designed to conduct infrared astronomy. And regardless of the specifics, these findings demonstrate the JWST's capabilities in studying exoplanets.
The telescope can analyse the light from distant stars that has passed through planetary atmospheres, revealing the chemical makeup of those atmospheres. This information helps astronomers understand the conditions on these planets and their potential for harbouring life.