Overview: the discoverer of a particular object has the privilege of suggesting a name to a committee that judges its suitability.
The discoverer of the numbered object is defined to be the same as the discoverer of the principal designation.
This discoverer is accorded the privilege of suggesting a name for his/her discovery. The discoverer has the privilege for a period of ten years following the numbering of the object.
The discoverer writes a short citation explaining the reasons for assigning the name.
Names are judged by the fifteen-person Committee for Small-Body Nomenclature (formerly the Small Bodies Names Committee) of the International Astronomical Union, comprised of professional astronomers (with research interests connected with minor planets and/or comets) from around the world.
Proposed names should be:
16 characters or less in length (including any spaces or punctuation)
preferably one word
pronounceable (in some language)
not too similar to an existing name of a minor planet or natural planetary satellite
Comets are first given the number of the year of observation
Next is the upper-case code letter identifying the halfmonth of observation during that year using the same procedure as minor planets.
Then comes another consecutive numeral to indicate the order of discovery announcement during that halfmonth
example, the third comet reported as discovered during the second half of February 1995 would be designated 1995 D3.
To distinguish between types of comets a prefix is added to the front of the name
A/ would precede a comet designation that actually refers to a minor planet (or asteroid)
P / for a periodic comet (defined to have a revolution period of less than 200 years or confirmed observations at more than one perihelion passage)
C/ for a comet that is not periodic (in this sense)
X/ for a comet for which a meaningful orbit can not be computed
D/ for a periodic comet that no longer exists or is deemed to have disappeared
If a comet is observed to return (or have its periodicity established by observation through aphelion or from identifications), the P/ (or D/) shall be preceded by an official sequential number (e.g., 1P/1682 Q1 = Halley), the list to be maintained by the Minor Planet Center and published in the Minor Planet Circulars. Subsequent recoveries shall be acknowledged with further designations only when the predictions are particularly uncertain.
This naming system is only approximate, however, because of misestimates and other irregularities.
Example: the brightest star in Gemini (the Twins) is Beta Geminorum (Pollux) while Alpha Geminorum (Castor) is only the second brightest star of the constellation.
Since the Greek alphabet only has 24 letters and many constellations have many more stars, Johann Bayer started using lower case letters from “a” to “z”, for the stars numbered 25 to 50, and then upper case letters from “A” to “Z”, for stars 51 to 76.
This is used when the naming is restricted to those stars visible to the naked eye.