PSO J318.5-22: Where the Nightlife Never Ends Discovered in 2013 using direct imaging, PSO J318.5-22 belongs to a class of planets called rogue planets. Wandering alone in the galaxy, they do not orbit a parent star. Not much is known about how these free-floating planets come to exist, but scientists theorise they may be failed stars or planets ejected from young systems after an encounter with another planet. These rogue planets glow faintly from the heat of their formation