Andromeda is 2.5 million light-years from the Milky Way, a short distance on the astronomical scale, close enough to be visible from Earth as a point of light, according to NASA, although its halo is invisible to the naked eye. view. . Scientists believe that the halo - the vast envelope of gas that surrounds the Milky Way - has already made contact with Andromeda. Their collision is expected to occur irretrievably within about 4.5 billion years, according to data from NASA scientists studying t