Not all planets are lucky enough to live in a neighborhood like our Solar System – some are doomed to roam the cosmos alone. Astronomers have now, for the first time, measured the mass of, and distance to, one of these lonely worlds.
The planet packs about a fifth of the mass of Jupiter, and is located a little under 10,000 light-years away from Earth, towards the center of our galaxy. That size suggests it most likely formed as part of a planetary system, before being exiled by a game of gravitational billiards.
Related: Record-Smashing Rogue Planet Caught Growing at 6 Billion Tons Per Second.









