Proxima Centauri is the closest star to the solar system, located just over 4 light years from Earth. Proxima Centauri, along with its stellar companions Alpha Centauri A and B, form a trinary star system.
First discovered in 1915 by Robert Innes, Proxima Centauri is considerably smaller than the sun, with only a little more than a 10th the mass and diameter. Proxima Centauri has a low luminosity and is not visible without the aid of instruments. The star is quite close to its neighbors, and their respective orbits leave a distance of only one-fifth of a light year between them.