What is an alpha star within a constellation?

Star names like Alpha Centauri are Bayer designations, in which stars are identified by a greek letter followed by the constellation. The catalog was created in 1603 by the German astronomer Johann Bayer. read more

Stars are roughly ordered according to their brightness. But there are some exceptions (in Bayer’s days the brightness of stars could not be measured with great accuracy, so he made some “mistakes”). But in most constellations, the Alpha star is the brightest star of the constellation. read more

Within a constellation, the stars are tagged with Greek letters in the order of their brightness. The "alpha" is the brightest star in that constellation. Note: The "constellations" aren't only the familiar stick-figures in the sky any more. read more

Alpha Centauri is the nearest star system to the Sun, located at a distance of only 4.37 light years or 1.34 parsecs from Earth. Alpha Centauri is the brightest star in Centaurus constellation and the third brightest star in sky. It is only slightly brighter than Arcturus in Boötes constellation and Vega in Lyra. read more