IC 10 is an irregular galaxy in the constellation Cassiopeia. It was discovered by American astronomer Lewis Swift on 8 October 1887. In 1935 Nicholas Mayall became the first to suggest that the object is extragalactic. Edwin Hubble suspected it might belong to the Local Group of galaxies, but its status remained uncertain for decades. The radial velocity of IC 10 was measured in 1962, and it was found to be approaching the Milky Way at approximately 350 km/s, strengthening the evidence for its membership in the Local Group. Its membership in the group was finally confirmed in 1996 by direct measurements of its distance based on observations of Cepheids; most estimates place the galaxy 2–3 million light years from Earth, with some estimates ranging from 1.5–4.5 million light years. Despite its closeness, the galaxy is rather difficult to study because it lies near the plane of the Milky Way and is therefore heavily obscured by interstellar matter.