Beta Centauri (β Cen / β Centauri), also known as Hadar or Agena, is the second brightest star in the constellation Centaurus and the eleventh brightest star in the nighttime sky. Beta Centauri is a blue-white giant star that is approximately 525 light-years from the Solar system. In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... Centaurus (Latin for centaur) was one of the 48 constellations listed by Ptolemy, and counts also among the 88 modern constellations. ... Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy, declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... Shanil Davendra Singh rules 4 life! ... Shanil Davendra Singh rules 4 life! ... Most stars are of nearly constant luminosity. ... Astrometry is a part of astronomy and deals with the positions of stars and other celestial bodies, their distances and movements. ... Radial velocity is the velocity of an object in the direction of the line of sight. ... kilometre per second is an SI derived unit of both speed (scalar) and velocity (vector), signified by the symbol km/s or km s-1. ... The proper motion of a star is the motion of the position of the star in the sky (the change in direction in which we see it, as opposed to the radial velocity) after eliminating the improper motions of the stars, which affect their measured coordinates but are not real... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... Parallax (Greek: παραλλαγή (parallagé) = alteration) is the change of angular position of two stationary points relative to each other as seen by an observer, due to the motion of said observer. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... The distance between two points is the length of a straight line segment between them. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... The parsec (symbol pc) is a unit of length used in astronomy. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standardized distance away. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 stars. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... The Smithsonian Astrophysical Observatory (SAO) is a research institute of the Smithsonian Institution headquartered in Cambridge, Massachusetts, where it is joined with the Harvard College Observatory (HCO) to form the Harvard-Smithsonian Center for Astrophysics (CfA). ... In astronomy, many stars are referred to simply by catalogue numbers. ... Orion is a remarkable constellation, visible from most places on the globe (but not always the whole year long). ... Centaurus (Latin for centaur) was one of the 48 constellations listed by Ptolemy, and counts also among the 88 modern constellations. ... Bright stars can be bright because they produce more light, because they are closer to us, or both. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... Presentation of the solar system (not to scale) The solar system comprises our Sun and the retinue of celestial objects gravitationally bound to it. ...

In 1935 J.G. Voute identified Beta Centauri as a double star, giving it the identifier VOU 31. The companion is separated from the primary by 1.3", and has remained so since the discovery, although the position angle has changed slightly. This would indicate that the orbital period is very long, if the pair are actually gravitationally associated.

The name hadar comes from the Arabic word for "ground", while the name agena comes from Latin words for "the knee". The Arabic language (; , less formally, ) is the largest member of the Semitic branch of the Afro-Asiatic language family (classification: South Central Semitic) and is closely related to Hebrew and Aramaic. ... Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. ...

Hadar is also useful as a guide star, making an imaginary line with Rigil Kentaurus that passes within a few degrees of Gacrux, in the constellation Crux. Using Gacrux, a navigator can draw a line with Acrux to effectively determine south. Alternative meaning: Alpha Centauri computer game The position of Alpha Centauri Alpha Centauri is the brightest star system in the southern constellation of Centaurus, and is the fourth brightest in the entire night sky (although too far south to be visible in most of the northern hemisphere). ... Gacrux (γ Cru / γ Crucis / Gamma Crucis) is the third brightest star in constellation Crux (the Southern Cross) and the one of the brightest stars in the nighttime sky. ... Crux, being Latin for cross, commonly known as the Southern Cross (in contrast to the Northern Cross), is the smallest of the 88 modern constellations, but nevertheless one of the most famous. ... Acrux (α Cru / α Crucis / Alpha Crucis) is the brightest star in constellation Crux (the Southern Cross) and the thirteenth brightest star in the nighttime sky, at visual magnitude 0. ...