Greek Letters

Greek letters are used in some star maps. This was started with Johann Bayer's Uranometer star maps in 1603 which introducted designating the brighter stars of each constellation by the small letters of the Greek alphabet. An example, is shown below for part of the constellation Ursa Major.

In general, the stars are lettered in order of brightness. In a constellation the brightnest star is (Alpha), the second brightest (Beta) and so on. That is why most of the First Magnitude Stars are designated Alpha and a few are designated Beta. When several stars in the constellation have nearly the same brightness, they are lettered in order of their positions in the figure, beginning at the head. For example, in the constellation of Ursa Major the bright stars are similar in brightness and therefore are lettered in order of postion from the head of the bear.

The full name of the star in the Johann Bayer system is the letter followed by the genitive (possessive) of the Latin name of the constellation. For example, the brightest star Sirius is designated Alpha Canis Majoris.