Ancient astronomers, starting with the ancient Greek Eudoxus and Wu Xian in China, made sense of the stars above by interpreting them as mythography; cataloged representations of mythology. This practice of mapping the heavens was known as uranography–named after Uranus, the Greek god of the heavens who was deposed by Zeus. We still use these today, although the scale of the cosmos has long outstripped astronomers’ ability to map it to human myths. Consider the constellation Orion:
Fig. An overview of the Orion constellation
Orion the hunter, contains
Betelgeuse, Arabic: “the giant’s shoulder”
Rigel, Arabic: “foot”
Bellatrix, a “female warrior” in Latin.
Meissa, Arabic: “the shining one”
Alnitak, Arabic: “east end of the belt”
Alnilam, Arabic: “middle of the belt”
Mintaka, Arabic: “west end of the belt”
Saif, Arabic: “hilt of the sword”
Nair al Saif, Arabic: “bright one of the sword” (blue supergiant)
Thabit, Arabic: the imperturbable one (a phallic reference?)
Rekbah al Jauza al Yemeniat, Arabic: “right knee of the giant” (now called Saiph)
Fig. Orion as a geometric aid to finding other stars and constellations.
Around 1603, astronomer Johann Bayer developed a less lyrical and more systematic indexing system, which involved applying the Latin genitive -is suffix to constellation name (indicating ownership, equivalent to the English apostrophe-s as in ‘Bob’s’), and replacing the personified star name with a Greek letter. Examples of this are Alpha Centauri, Beta Centauri, Gamma Centauri, and so on, including the globular cluster Omega Centauri, which isn’t a star at all. The order of the Greek letters represented the relative brightness of the star within its host constellation; i.e. Alpha Centauri is the brightest, Beta Centauri second-brightest, etc. This list enumerates the stars of the constellation Centaurus (the centaur) in the southern hemisphere.
When applied to Orion, Bayer renamed Betelgeuse to Alpha Orionis, and Rigel to Beta Orionis. Unfortunately, Rigel is brighter than Betelgeuse, so users of the Bayer system have to keep this system exception in mind. Tracking these details distinguishes the serious professional from the dabbler.
In the late 1600s, astronomer John Flamsteed may have observed that people do not have the order of Greek letters memorized, and the Greek alphabet is limited to 24 letters. He replaced the letters with numbers, giving us star names such as 51 Pegasi and 61 Cygni. 34 Tauri was cataloged as a star in Taurus but was actually the planet that in the future would be named Uranus–an ironic victim of uranological error. Benjamin Gould added his own eponymous flair in his 1879 catalog of the southern hemisphere, which added a G, as in 82 G. Eridani.
Later it became fashionable to use three-letter abbreviations for the constellation names. Betelgeuse became ⍺ ORI or 58 Ori, Rigel became ꞵ Ori or 19 Ori.
Eventually, it was realized that the constellations were human projections, and the stars within them may be separated by millions of light years rather than connected together. The largest star catalogs today contain a billion stars, yet are a tiny fraction of the total number of stars in the universe. In computerized catalogs such as the Guide Star Catalog developed for the Hubble Space Telescope, astronomers no longer access the stars by constellation name. Instead they must specify a numerical sky coordinate window for computer software to retrieve the stars within on the astronomer’s behalf. The era of astronomers getting to know the “social structure” of stars in their neighborhoods is long over, replaced by indexes suitable for computers to track stars in their angular coordinate memories, but not for humans to map them in their content-addressable and graph-oriented memories. This has been the price of progress.
Yet everyone from astronomers to the public has retained the mythological names, not from a sense of historical nostalgia, but because they are useful. The personifications make each star unique, connects to them to their scientific history, bind their descriptive properties (Orion is a hunter, Betelgeuse is a seething red supergiant, Rigel is a bright blue supergiant), and situate them spatially within imagined pathways and skeleton physics schemas. This is more aligned to how our brains work.
