For the first time, an exoplanet has been discovered to have a stratosphere, not unlike Earth. The planet, known as WASP-121b (pictured in the illustration) belongs to a class called "hot Jupiters" and is around 880 light-years away. Its upper atmosphere of glowing water molecules was detected using the Hubble Telescope.
The world is enormous, about the size of two Jupiters, and is so hot that iron could boil in its atmosphere. More at Space.com and The Verge.