Meet HD 209458 b, a gas giant so close to its star that its atmosphere is boiling off into space. This planet, nicknamed “Osiris,” is losing mass at a rate of 10,000 tons per second. The escaping gas forms a giant tail, like a comet, stretching for thousands of miles. Eventually, the planet could be stripped down to its rocky core—if it even has one. In the meantime, it’s a rare example of a planet actively being destroyed by its own sun.