HomeTaurusAldebaranAldebaran Star Facts (Alpha Tauri) By : John Whitworth / Updated : 29-03-2026 11:41 pm ContentsObservationDistanceSize (Radius, Mass)ExoplanetFactsAldebaran, also known as Alpha Tauri is the brightest star in the constellation of Taurus, the Bull hence its Bayer designation. It is a GiantOrange star, one that has or is moving out of the Main Sequence Stars stage of its life.It is probably mistaken by some to be the location of Alderaan, the planet in the Star Wars franchise because their name starts the same.Aldebaran's name means "The Follower". Aldebaran’s name was given to imply it followed the Pleiades, the seven sisters Star Cluster across the sky. The star is located closer to Earth than any of the sisters. Due to its brightness, it is referred to as the "Eye of the Bull".The N.A.S.A. space probe Pioneer 10 is heading in the general direction of Aldebaran, but contact has been lost with the probe. It will take many thousands, or even millions, of years to get there, so even if we hadn't lost contact, we would still be waiting a long time for it.If you were to search for Alpha Tauri in Bing or Google, you would come across Scuderia Alpha Tauri, an Italian Formula One racing team and constructorObservationAldebaran is best observed in the winter months. It should be easy to identify due to its proximity to Orion, which is probably the easiest to recognise constellation in the night sky. Once you have identified Orion, look roughly up from the shield, and you should see the constellation of Taurus. Aldebaran is one of the eyes of the bull.Although Aldebaran is in the northern celestial hemisphere, it doesn't mean that it can't be observed in the southern hemisphere also; it's just a little harder.The months best to observe Aldebaran are between mid-November and May of the following year. You won't need a pair of binoculars or a telescope to be able to see the star.DistanceAldebaran is located 66.65 light-years from us, meaning that the light has taken 66.65 years to reach here. We don't have faster-than-light travel, as depicted on television and in films, so it is too distant for us ever to reach.The fastest probe that we currently have is the New Horizons mission to Pluto which travels at 36,400 mph. That would take in excess of 1.23 million years to get to Aldebaran if it were travelling in the same direction as the star.Size (Radius, Mass)Aldebaran has a radius that is 45.1 times that of our own star, The Sun and with a mass that is 1.16 times that of our Sun. Although you might expect that a star with that much greater radius should have much more mass than our star, 1.16, the small amount can be explained by it being larger; the gases aren't as dense.ExoplanetIt was first announced that Aldebaran had a planet, then it was discounted as an error in the data. The planet was confirmed again in 2015 using the Radial Velocity method, which detects minute differences in motion. AAS NovaIn 2019, four years later, a paper was then published, which cast doubt again on whether the star has a planet or not. The uncertainty about whether a planet exists will persist for some time. It was, but it wasn't, with each paper being the definitive answer on Aldebaran's planets.Other large stars with planets include Pollux and Hamal, but Aldebaran is larger than both. The planet would be a gas planet and would be many times the size of Jupiter. If we had Aldebaran instead of the Sun as our star, it would reach out to halfway between the Sun and Mercury. Our planet would be less likely to have life because it'd be too hot. Ref: Illionois UniversityAldebaran bAldebaran c Aldebaran FactsAny red fact description is not peer reviewed; it is estimated using other pieces of facts, e.g. temperature if in red is based on the colour of the star.General FactsPrimary NameAldebaranAlternative NamesAlpha Tauri, Alf Tau, Alpha Tau, Ad-Dabaran, HD 29139, EPIC 246875074, TYC 1266-1416-1, HIP 21421, HR 1457, 87 Tauri, 87 Tau, BD +16 629, Gliese 171.1 A, 2MASS J4355524-1630331, IRAS 4330+1624Spectral TypeK5IIIStar TypeLong Period Variable StarColour orange to red GalaxyMilky WayConstellationTaurusMain StarYesAge 6.4 million years Age Range5.3 - 7.8 billion yearsAbsolute Magnitude if(AbsMag1997.HasValue) { -0.63 } / / -0.68 Visual / Apparent Magnitude0.87Visible From Earth YesRight Ascension (R.A.)04h 35m 55.20Declination (Dec.)+16° 30` 35.1Galactic Latitude-20.24813798 °Galactic Longitude180.97141881 °1997 Distance from Earth50.09 Parallax (milliarcseconds) 65.12 Light Years 19.96 Parsecs2007 Distance from Earth48.94 Parallax (milliarcseconds) 66.65 Light Years 20.43 Parsecs 4213960.6283423028 Astronomical UnitsGalacto-Centric Distance24198.05849136 Light Years / 7419 ParsecsProper Motion Dec.-188.94 ± 0.43 milliarcseconds/yearProper Motion RA.63.45 ± 0.77 milliarcseconds/yearB-V Index1.53Radial Velocity54.26 ± 0.03 km/sIron Abundance (Fe/H)-0.17 ± 9.99Eccentricity0.1645Semi-Major Axis7280Luminosity (Lsun)439 Mass (Sol...