Aldebaran (Arabic: “The Follower”, "الدبران") is a star located in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldebaran varies in brightness from an apparent visual magnitude 0.75 down to 0.95, making it the brightest star in the constellation, as well as (typically) the fourteenth-brightest star in the night sky. It is positioned at a distance of approximately 65 light-years from the Sun. The star lies along the line of sight to the nearby Hyades cluster. Aldebaran is a red giant, meaning that it is cooler than the Sun with a surface temperature of , but its radius is about 44 times the Sun's, so it is over 400 times as luminous. As a giant star, it has moved off the main sequence on the Hertzsprung–Russell diagram after depleting its supply of hydrogen in the core. The star spins slowly and takes 520 days to complete a rotation. Aldebaran is believed to host a planet several times the mass of Jupiter, named . The planetary exploration probe Pioneer 10 is heading in the general direction of the star and should make its closest approach in about two million years. Nomenclature The traditional name Aldebaran derives from the Arabic al Dabarān ("الدبران"), meaning "the follower", because it seems to follow the Pleiades. In 2016, the International Astronomical Union Working Group on Star Names (WGSN) approved the proper name Aldebaran for this star. Aldebaran is the brightest star in the constellation Taurus and so has the Bayer designation α Tauri, Latinised as Alpha Tauri. It has the Flamsteed designation 87 Tauri as the 87th star in the constellation of approximately 7th magnitude or brighter, ordered by right ascension. It also has the Bright Star Catalogue number 1457, the HD number 29139, and the Hipparcos catalogue number 21421, mostly seen in scientific publications. It is a variable star listed in the General Catalogue of Variable Stars, but it is listed using its Bayer designation and does not have a separate variable star designation. Aldebaran and several nearby stars are included in double star catalogues such as the Washington Double Star Catalog as WDS 04359+1631 and the Aitken Double Star Catalogue as ADS 3321. It was included with an 11th-magnitude companion as a double star as H IV 66 in the Herschel Catalogue of Double Stars and