NGC 7331 (the Salt Pan Group) and NGC 7320 (Stephan's Quintet)

NGC 7331 Distance from Earth: 39,790,000 light-years NGC 7320 Stephan's Quintet is a group of five galaxies in the constellation Pegasus. Four of them form a compact galaxy group, while the fifth galaxy is only projected onto the group. Four of the five galaxies in Stephan's Quintet are in constant interaction. NGC 7320 is located approximately 39 million light-years from Earth, while the other galaxies in the quintet are at distances of 210–340 million light-years. In the 1970s, some astronomers, most notably H. Arp, believed that the distance to all galaxies in the quintet, including NGC 7320, was 20 megaparsecs.