Proxima Centauri is a small, low-mass star located 4.2465 light-years away from the Sun in the southern constellation of Centaurus. Its Latin name means the 'nearest [star] of Centaurus'. It was discovered in 1915 by Robert Innes and is the nearest-known star to the Sun. With a quiescent apparent magnitude 11.13, it is too faint to be seen with the unaided eye. Proxima Centauri is a member of the Alpha Centauri star system, being identified as component Alpha Centauri C, and is 2.18° to the southwest of the Alpha Centauri AB pair. It is currently 12,950 AU from AB, which it orbits with a period of about 550,000 years. Proxima Centauri is a red dwarf star with a mass about 12.5% of the Sun's mass, and average density about 33 times that of the Sun. Because of Proxima Centauri's proximity to Earth, its angular diameter can be measured directly. Its actual diameter is about one-seventh the diameter of the Sun.