Hyper-velocity star US 708, illustration. This freely moving star is around 62,000 light years from Earth in the constellation of Ursa Major. Discovered in 1982, in the halo of the Milky Way, it is a hot sub-dwarf of spectral type B. It is the fastest moving object in our galaxy, and will one day leave the galaxy (as shown here). It is thought to have been ejected from a binary system by a supernova.