GJ 1214 b

GJ 1214 b, formally named Enaiposha since 2023, is a hot sub-Neptune orbiting the star GJ 1214, about 48 light-years away in Ophiuchus. It was discovered in December 2009.

When it was found it was the best known candidate for an ocean planet and was often called a waterworld, but James Webb Space Telescope observations suggest it more likely has a thick envelope of hydrogen, helium, water and other volatiles. It was the second planet between Earth and Neptune in mass to have both its mass and radius measured, and because it transits a nearby star its atmosphere can be studied by spectroscopy.