The Andromeda Galaxy is 2.3 million light years away and is one of the most distant objects visible to the unaided eye. It is also the nearest spiral galaxy to the Milky Way, which it resembles in size and form. None of these facts were known before the 1920s, when the US astronomer Edwin Hubble (1889-1953) identified many fuzzy shapes in the sky as distant galaxies like our own. The Andromeda Galaxy contains 100,000 million stars and is one of a similarly unimaginable number of galaxies in the universe.