Science: Discovered in 2013, PSO J318.5−22 is a rogue planet—meaning it doesn't orbit any particular star. It's also a gas giant with a mass eight times that of Jupiter. Although such planets are mostly thought to have been ejected from the stellar systems in which they formed, it's possible that some other mechanism led to their formation and isolation. Because they aren't orbiting stars, rogue planets provide a study opportunity for scientists, who can observe them without being overwhelmed by stellar light. Researchers using the European Southern Observatory's New Technology Telescope in Chile have found that shifts in PSO J318.5−22's brightness indicate the planet completes a rotation once every five hours and has clouds with temperatures of about 800 °C. Those clouds could produce molten-iron rain. The discovery marks the first time that a specific type of weather has been identified on an extrasolar planet.
