The naming of stars

Stardust image of asteroid AnnefrankStardust image of asteroid Annefrank, just prior to closest approach. Image: NASA / JPL The Royal Observatory, Greenwich is often asked how stars may be named after individuals. There are commercial firms who will, for a sum, prepare certificates which appear to name a star, or other celestial body, after someone living or dead. Unfortunately the name so-given has no authorization and will not be used by astronomers.

The only official body which can give names to astronomical objects is the International Astronomical Union (IAU). The IAU has asked astronomers not to further the activities of these firms and so the RGO will not give out any information on their activities.

All official names have to be adopted by the IAU. There are certain rules which have to be followed in the official names allocated to different types of object; some of these are outlined below.

Stars

Traditional names for the brightest stars come from the old Arabic names. Some bright stars have either Flamsteed numbers or Greek letters assigned originally by Bayer. Other stars are generally referred to by a catalogue number.

There is a very small number of stars which are named after individual astronomers. This is in honour of the named astronomer's outstanding work on that particular star.

Comets

The nucleus of comet HalleyThe nucleus of comet Halley as seen by the Giotto space probe. Image: ESA/MPAE Comets are named after their discoverers. Sometimes there is more than one independent discoverer and the comet then generally bears their combined names. In addition to this name comets are given a provisional number which indicates the year of discovery and their order of discovery. Later a permanent number is given which indicates the year of perihelion passage and the order in that year.

In 1994, the International Astronomical Union updated their mechanism for naming comets – comets now receive a designation consisting of the year of observation, an upper-case code letter identifying the halfmonth of observation during that year according to the procedure used for minor planets, and a consecutive numeral to indicate the order of discovery announcement during that halfmonth. For example, the third comet reported as discovered during the second half of February 1995 would be designated 1995 D3. A prefix may also be added to indicate the nature of the comet, as shown in the following table:

Prefix Meaning
P/ periodic
C/ not periodic
A/ minor planet (asteroid)

A prefix of X/ indicates a comet for which an orbit cannot be computed, while D/ indicates a comet which has broken up or disappeared. For more information on comet designations, please visit the International Astronomy Union website, a link to which is available on the right hand column of this page.

Minor planets

The naming of minor planets is complex. The earliest discoveries were given names from classical mythology and from contemporary life. Nowadays the privilege of naming a new minor planet rests with the discoverer. Each is also given a provisional number indicating when it was found and, after its orbit has been determined, it is given a permanent number. Providing that there is no duplication more or less any name may be used (for instance the four members of the Beatles have minor planets named after them, as does James Bond).

Planetary and lunar features

Io passing over JupiterIo passing over Jupiter. Image: J. Spencer & NASA The naming of the features on the various planets and their moons has been undertaken using different themes for each with attempts being made to keep the themes within some kind of framework. For example, all of Jupiter's satellites are named after mythical loves of Zeus, the moons of Uranus are fairies and/or Shakespearean women and the features on the surface of Venus are all named after famous women (all deceased, non-political and non-religious).

Other objects

Other objects are given catalogue names. Some of the catalogues have the discoverer's name while others take the name of the discovering institution or telescope or simply that of the person/people/institution making the catalogue.