"Hubble Discovers Water Vapor in Atmosphere of Tiny Exoplanet"

The Hubble Space Telescope has detected water vapor in the atmosphere of exoplanet GJ 9827d, the smallest planet outside our solar system to exhibit this feature. This "landmark discovery" brings astronomers closer to characterizing Earth-like worlds. The planet, about twice Earth's diameter, orbits a red dwarf star 97 light-years away and may be a "mini-Neptune" with a hydrogen-rich atmosphere containing water. The finding opens the door to future study of similar planets, especially by the James Webb Space Telescope, and has been published in The Astrophysical Journal Letters.