Alpha Centauri is the brightest star in the constellation of Centaurus. It is a triple star system located 4.37 light-years from Earth, making it the closest star system to our Solar System. Alpha Centauri is the third brightest star in the night sky and can be seen with the naked eye. It is composed of two stars, Alpha Centauri A and Alpha Centauri B, which are both visible to the naked eye, and a third star, Proxima Centauri, which is too faint to be seen without a telescope.