Rigel (), also designated Beta Orionis (β Orionis, abbreviated Beta Ori, β Ori), is generally the seventh-brightest star in the night sky and the brightest in the constellation of Orion—though occasionally it is outshone within the constellation by the variable star Betelgeuse. With an apparent magnitude of 0.13, it is a luminous object some 863 light-years distant from Earth. Rigel as seen from Earth is actually a multiple star system of three to five stars, the primary star (Rigel A) being a blue-white supergiant which is estimated to be anywhere from 120,000 to 279,000 times as luminous as the Sun, depending on the method used to calculate its properties. It has exhausted its core of hydrogen and swollen to between 79 and 115 times the Sun's radius. It pulsates quasi-periodically and is classified as an Alpha Cygni variable. A companion, Rigel B, is 500 times fainter than the supergiant Rigel A and visible only with a telescope. Rigel B is itself a spectroscopic binary system, consisting of two main sequence blue-white stars of spectral type B9V that are estimated to be respectively 3.9 and 2.9 times as massive as the Sun; Rigel Bb may itself be a binary. Rigel B also appears to have a very close visual companion Rigel C of almost identical appearance.