Astronomy

Astronomer uses genitive forms of the names of constellations, preceded by a Greek letter, to designate about 1300 bright stars. The system was introduded by Johannes Bayer around the year 1600 to name the brighter stars. The basic rule was to name them in order of brightness, but the rule is more often violated than not. Now, the designations commonly also depending on the positionings of the stars within their constellations.

To the Greek letter is appended the Latin possessive form of the constellation name, Vega, the Alpha star (the brightest star) of Lyra, becoming Alpha Lyrae; Rigel, the second brightest star of Orion becoming Beta Orionis, and so on.

Following is the order of greek letters used to naming the stars:

 1. Alpha    2. Beta    3. Gamma    4. Delta    5. Epsilon
 6. Zeta     7. Eta     8. Theta    9. Iota    10. Kappa
11. Lambda  12. Mu     13. Nu      14. Xi      15. Omicron
16. Pi      17. Rho    18. Sigma   19. Tau     20. Upsilon
21. Phi     22. Chi    23. Psi     24. Omega

Because Bayer left off with the Latin upper case “Q”, this system used the Roman alphabet, and went from “R” on, so to aleviate any confusion between designation types (like R Coronae Borealis).

This system worked well until celestial photography caught on, which introduced more stars than there were variables to name them. So, it was adapted first to include double letters, and then finally (when they ran out of those, too) letter-number combinations. Some examples of this method are YY Geminorum or V348 Sagitarii.

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