Two very different galaxies are featured in this space wallpaper taken by the NASA/ESA Hubble Space Telescope—forming a peculiar galaxy pair called Arp 116. Arp 116 is composed of a giant elliptical galaxy known as Messier 60, and a much smaller spiral galaxy, NGC 4647. Astronomers have long tried to determine whether these two galaxies are actually interacting. Although they overlap as seen from Earth, there is no evidence of new star formation, which would be one of the clearest signs that the two galaxies are indeed interacting. However, recent studies of very detailed Hubble images suggest the onset of some tidal interaction between the two. This image was released Sept. 6, 2012.
(Image: © NASA, ESA)