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# 12.2 Star Names

Naming stars has been a part of astronomy since astronomy and astrology were a single science, thousands of years ago. Today, the International Astronomical Union (IAU) is the only official body allowed to name stars, but historically the task of naming stars belonged to mystics and then to map makers. The oldest known catalog of Western stellar names was created by Hipparchus, a Greek astronomer, in roughly 150 B.C. and was incorporated into Ptolemy's "Almagest" in approximately 150 A.D. It contained a catalog of 1022 stars and star names, and remains a main source of astronomical knowledge from antiquity. About a thousand years ago, the Almagest was passed on through Europe by Arabian astronomers. As a result, many of the brightest stars ended up with Arabic names. Since al- is the common Arabic article, many star names start with this prefix: Algol, Aldebaran, Altair, Alcor. (Other scientific words also have Arab origins: algebra, alchemy, alkali, and almanac.)

Another reason that so many bright stars have Arabic names is connected with the nature of travel in desert countries. With blistering heat during the day, people in the Middle East used to travel at night, and so they became familiar with the stars of the night sky as navigation aids. With trade and commerce, their names were passed on and used by other cultures. Also, when Europe went through its Dark Ages, science went into decline and much Greek knowledge was lost. Arab astronomers not only carried the flame of Greek thought, they made substantial discoveries and innovations to move the field forward.

Only the very brightest stars — those visible to the human eye — in the night sky have names. These names have their origin in the mythology of a variety of cultures. The fourth brightest star in the sky, Vega, has 40 different recorded names! Most of the brightest stars have names and meanings from Green and Roman times. Sirius means "scorching," quite appropriate for the brightest star in the sky. Procyon comes from "pro kion," Greek for before the dog, because it rises ahead of Sirius, the dog star. Arcturus is the "bear driver," following the Great Bear constellation as it circles the north celestial pole. Castor and Pollux are famous warrior twins in Greek mythology. Other prominent stars, like Polaris, are Latin names.

There are about 6000 stars visible to the naked eye under the best viewing conditions. The stars in the Almagest were included in the next modern mapping, including 1200 stars, which was done by Johann Bayer, who used the "Uranometria" to expand this list to include scores of additional stars, including 12 new southern constellations. Having several hundred stars with names created a problem; imagine memorizing the names and locations of several hunded people! Bayer's maps introduced the naming convention of using the greek alphabet in combination with the genitive (possessive) form of a constellation name to identify stars with constellations. So, Aldebaran becomes α Tauri. It is often mistaken believed that the names place the stars in order of brightness, so α Orionis should be brighter than β Orionis. The truth is, that while this sometimes happened, the ordering is only loosely in order of brightness, and is based on both position (north versus south), brightness, and location (head versus feet) of a star in a constellation.

As surveys of stars continued and catalogs grew, new naming conventions were needed. The great English astronomy John Flamsteed listed stars by position within a constellation, ordered by right ascension (the analog for longitude on the celestial sphere). So 1 Cygni is the western-most star in the constellation Cygnus, 2 Cygni is the second most westerly, and so on. The many stars fainter than the eye can see are usually anonymous; astronomers give them labels based on the coordinates that describe their position on the sky. Those positions may be preceded by an abbreviation of the catalog name, such as BD for the Bonner Durchmusterung catalog from Germany in the 19th Century, and HD for the Henry Draper catalog from the early 20th Century.

You may see advertisements allowing you to pay to name a star after yourself or a friend, but these names have no scientific legitimacy and are not acknowledged by the International Astronomical Union, the governing body of astronomy. No one can ""own"" a star — the night sky belongs to all of us.

"," but these names have no scientific legitimacy and are not acknowledged by the IAU. Modern star catalogs do not use proper names; they typically use abbreviations of the catalog name followed by a number. No one can ""own"" a star — the night sky belongs to all of us.

Alpha Centauri and the Southern Cross. Click here for original source URL.