Alpha Centauri C, or Proxima Centauri, is a small and faint red dwarf (Class M). Though not visible to the naked eye, Proxima Centauri is the closest star to the Sun at a distance of 4. 24 light-years (1. 30 pc), slightly closer than Alpha Centauri AB. Currently, the distance between Proxima Centauri and Alpha Centauri AB is about 13,000 astronomical units (0. 21 ly), equivalent to about 430 times the radius of Neptune's orbit. Proxima Centauri b is an Earth-sized exoplanet in the habitable zone of Proxima Centauri; it was discovered in 2016.