Not every large object in space forms part of a solar system. There are some big objects that exist in isolation in space, without either being a star or orbiting one. One of these, SIMP 0136, wanders aimlessly in the Milky Way, about 20 light years away from Earth. It has a mass about 13 times that of Jupiter, and is thought to have the structure and chemical composition of a giant gas planet, though its true characteristics have not yet been determined.
Such untethered objects are typically classified either as “free-floating planets,” which form inside a star system, but are thrown out by