Rogue planet

Planet not gravitationally bound to a star

A rogue planet, also termed a free-floating planet (FFP) or an isolated planetary-mass object (iPMO), is an interstellar object of planetary mass which is not gravitationally bound to any star or brown dwarf. Rogue planets may originate from planetary systems in which they are formed and later ejected, or they can also form on their own, outside a planetary system. The Milky Way alone may have billions to trillions of rogue planets, a range the Nancy Grace Roman Space Telescope is expected to refine.

From Wikipedia, under CC BY-SA. More on occurri.