How Are Minor Planets Named?
The quick version: the discoverer of a particular object has the privilege of
suggesting a name to a committee that judges its suitability. Contrary to some
recent media reports it is not possible to buy a minor planet. If you
have a name you would like to apply, the best advice is
"Go out and discover one!". Information on how
this might be achieved is available
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.
- The assignment of a particular name to a particular minor planet is the end
of a long process that can take many decades.
- 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 have been reported
to the Minor Planet Center, a new provisional
designation is assigned to the object. These two nights do not need to come
from the same observer.
- 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 chosen by the identifier as the principal designation. The selection of which
designation is chosen has no effect on who will be the discoverer when the object
- 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.
- 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 in one of two ways:
- For objects that had multiple-opposition orbits prior to the issuance
of MPEC 2010-U20,
the discover of the numbered object is the same as the
discoverer of the principal designation.
- For objects that became multi-opposition after that MPEC, the
discoverer of the numbered object is the observer who made the earliest-reported
observation at the opposition with the earliest-reported second-night observation.
- 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
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
- preferably one word
- pronounceable (in some language)
- not too similar to an existing name of a minor planet or natural
- 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.
- Certain classes of names are to be applied to specific orbital classes
of minor planets.
- Objects in the classical TNO belt are to receive names of creation
- Objects in orbits in 3:2 resonance with Neptune are to receive
names of underworld deities.
- Objects in orbits between the orbits of Jupiter and Neptune, and
not in 1:1 resonance with any major planet, are to receive names
- Objects in 1:1 resonance with Jupiter are to receive names associated
with the Trojan War. Objects at the preceding L4 point are named for
Greeks, objects at the trailing L5 point are named for Trojans.
- Near-Earth Objects are to receive names from mythology, except names
associated with creation or underworld themes.
- 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.