How Are Minor Planets Named?

A fuller description of how minor planets are named is given below, but you will need to understand some basic astronomical concepts in order to fully appreciate it.

1. The assignment of a particular name to a particular minor planet is the end of a long process that can take many decades.

2. It begins with the discovery of a minor planet that cannot be identified with any already-known multiple-opposition or recent single-opposition object. When observations on two nights of a new object are available they are reported to the Minor Planet Center, which assigns a provisional designation to the object.
   • At this stage, it is possible to search for identifications with previously-discovered provisionally-designated objects observed at only one opposition in the past. If an identification is made, one of the provisional designations is defined to be the principal designation. This is generally the earliest opposition at which a reasonable orbit was computed. By "reasonable", we mean an orbit that is good enough to use as a starting orbit to link the other observations. Generally, an arc of one month will be sufficient, arcs of more than two weeks generally sufficient. Objects with arcs shorter than two weeks often aren't good enough to be principal designations. But these are only guidelines and each case is handled on a case-by-case basis.

   • If no identifications are forthcoming, further observations of the new object are obtained and an orbit is computed. The object is followed for as long as possible at the discovery opposition (some objects are followed for three or four months). Additional searches for identifications can be made as each new set of observations is obtained. If any identifications are made one of the designations involved is chosen as the principal designation.

   • If no identifications are found and the observed arc reaches two or three months, it is likely that the object may be found as a result of a direct search at the next opposition.

3. Further observations are made of the object at later oppositions. When there are observations at four or more oppositions the object may receive a permanent designation, a number. (The actual circumstances under which objects are numbered are rather complex and subject to occasional revision, but four well-observed oppositions will usually suffice.) For unusual objects, such as NEAs (Near-Earth Asteroids), numbering might occur after three, maybe even only two, oppositions.
   • 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.

4. 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)
     • non-offensive
     • not too similar to an existing name of a minor planet or natural planetary satellite

   • Names for persons or events known primarily for their military or political activities are acceptable only after 100 years elapsed since the person died or the event occurred.

   • Names of pet animals are discouraged.

   • Names of a purely or principally commerical nature are not allowed.

5. Accepted names become official when they are published, along with their accompanying citations, in the Minor Planet Circulars, issued monthly by the Minor Planet Center (an official service of IAU Commission 20).

An alphabetical list of minor-planet names is available.

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