For the first time, astronomers have detected actual weather systems on a planet beyond the Solar System. Orbiting the star HAT-P-7, 1000 light-years away, is a gas giant 16 times larger than Earth. Called HAT-P-7b, the planet is so close to its star that the dayside temperature is much hotter than the night side. This imbalance drives a fast jet stream, made up of clouds of corundum (from which rubies and sapphires are made). The night side is largely covered in clouds. But as they are pushed onto the dayside by the rapid winds, they quickly evaporate, leaving the day side largely devoid of features.