How Do Stars Get Their Names? Arabic Words, Greek Letters and a Database

Most traditional star names in European use are Arabic in origin, which reflects the transmission of astronomy through the Islamic world during centuries when Greek texts were preserved, translated and extended there and then passed into Latin Europe. Many describe the star's position within a constellation figure, so a name may mean the shoulder, the tail, the hand or the mouth of the animal, which is how Betelgeuse, Deneb, Altair and Fomalhaut arose. The forms that survive in English are frequently corrupted, having passed through transliteration into Latin, manuscript copying errors and re-transliteration, so several familiar names are garbled beyond easy recognition of the original words, and Betelgeuse is a well-known case where a misread letter changed the meaning entirely. A smaller set of names is Greek or Latin, including Sirius and Regulus, and a handful come from other traditions. Only a few hundred stars have proper names at all, which is a tiny fraction of those visible through any instrument.

Several numbering schemes coexist, each created for a different purpose and none ever retired:

• •Bayer letters, assigned in 1603, giving Greek letters within each constellation roughly in order of brightness, so the brightest star in a constellation is usually its alpha, with enough exceptions to be unreliable
• •Flamsteed numbers, assigned in the eighteenth century, numbering stars within each constellation in order of position across the sky rather than by brightness
• •Variable star designations, using a peculiar lettering scheme starting at R and continuing through awkward combinations, which exists because the early letters were already taken
• •Catalogue numbers from major surveys, including Henry Draper, Hipparcos, Tycho and Gaia designations, which are the identifiers actually used in research
• •Coordinate-based names, which encode position directly into the designation and are standard for objects found by modern surveys
• •Double star and cluster designations, which follow their own conventions and add further layers for the same physical object

The International Astronomical Union is the recognised authority for astronomical naming, and it established a working group on star names in 2016 that produced an official catalogue of approved proper names, fixing spellings that had varied for centuries and assigning names to specific components of multiple star systems where the traditional name had been ambiguous. It also runs public naming campaigns, notably for exoplanets and their host stars, which have produced official names drawn from many cultures and languages and represent a deliberate effort to broaden a nomenclature that was overwhelmingly Arabic, Greek and Latin. The body is equally clear about what is not official, and star naming companies that sell certificates have no standing whatsoever, since the names they issue appear in no catalogue used by anyone and confer nothing. That business has been the subject of consumer protection action in several countries for implying official recognition, and astronomical organisations publish explicit statements about it, which has done little to reduce sales.

Naming has become genuinely contested in several areas. Planetary feature names follow themed conventions approved by the same body, so craters on one world are named for artists and on another for scientists, and the selection has been criticised for its historical skew towards European men. Several named features and objects honour individuals whose records are now regarded as objectionable, and the question of renaming has been raised repeatedly, with one telescope's name the subject of a sustained and public dispute. Constellation boundaries themselves were only fixed in 1922 and 1930, dividing the sky into eighty-eight regions with precise borders, which turned constellations from figures into defined areas and settled centuries of variation, and the selection preserved the Greek tradition while discarding numerous later inventions that had flattered patrons. Indigenous sky traditions name and organise the stars entirely differently, including dark constellations defined by the absence of stars in the Milky Way, and astronomical organisations have begun documenting these rather than treating the Western scheme as the sky's only description.

Most traditional names are Arabic, frequently describing a position in a constellation figure, and they reached English through layers of transliteration and copying errors that garbled several beyond recognition. Bayer letters from 1603 run roughly by brightness and Flamsteed numbers by position, with catalogue numbers underneath. The international body fixed official spellings in 2016, and commercial star naming confers nothing.