Scientists peer into the atmosphere of a mysterious sub-Neptune and make a surprising discovery

Researchers thought they had a good idea of what the atmosphere of a sub-Neptune looks like. But new research turns everything upside down.

The study, published in The Astrophysical Journal Letters, focuses on the atmosphere of sub-Neptune TOI-421b, which unexpectedly contains light molecules.

Sub-Neptunes are estimated to be the most common type of planet in the universe, yet little is known about them. The James Webb Space Telescope has now provided new insights, revealing a hydrogen-rich atmosphere in TOI-421b, contrary to earlier findings of heavier molecules in cooler sub-Neptunes.