Proxima Centauri lies in the constellation of Centaurus (the Centaur), just over four light-years from Earth. Although it looks bright through the eye of the Hubble Space Telescope, as you might expect from the nearest star to the solar system, Proxima Centauri is not visible to the naked eye. Its average luminosity is very low, and it is quite small compared to other stars, at only about an eighth of the mass of the Sun. These observations were taken using Hubble's Wide Field and Planetary Camera 2 (WFPC2) in 1996. Proxima Centauri is actually part of a triple star system – its two companions, Alpha Centauri A and B, lie out of frame.