NASA’s James Webb Space Telescope has detected water vapor in the atmosphere of TOI-421 b, a scorching sub-Neptune planet about 244 light-years away.

This marks a breakthrough in studying these mysterious planets, which have no equivalent in our solar system.

Unlike previous sub-Neptunes that showed featureless spectra likely due to haze, TOI-421 b’s hot, clear atmosphere revealed water, possible carbon monoxide and sulfur dioxide, and a hydrogen-rich composition similar to its host star, Space.com has reported.

The findings challenge existing theories and offer new insights into how sub-Neptunes form and evolve.

Written by B.C. Begley