Minor planet names

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Minor planet names, including those of asteroids and dwarf planets, are managed by the Minor Planet Center, a branch of the IAU. They consist, in their final form, of a number originally assigned in approximate order of discovery, now assigned only after the orbit is determined, coupled with a name, which may be provisional or assigned by its discoverer,^[1] with the syntax (Number) Name, e.g. (50000) Quaoar or (90377) Sedna. The parentheses may be dropped, abridging the designation to 50000 Quaoar or 90377 Sedna, according to the preference of the astronomer or journal. In practice, however, the number is mostly a catalogue entry for any reasonably well-known object, and may be dropped completely.

The convention for satellites of minor planets (e.g (87) Sylvia I Romulus) is an extension of the Roman numeral convention that had been used, on and off, for the moons of the planets since Galileo's time.

Comets are also managed by the Minor Planet Center, but use a different cataloguing system.

[edit] History

By 1851 there were 15 asteroids, all but one with their own symbols. These were getting increasingly complex, and, as they had to be drawn by hand, astronomers found some of them difficult.

This difficulty was addressed by Benjamin Apthorp Gould in 1851, who suggested numbering them in order of discovery, and writing these numbers in circles instead. This practice was quickly taken up, and rapidly became incorporated into an official designation as the number of minor planets increased. It was soon (c1858) simplified to the number in parentheses, followed by the name: "(4) Vesta", with a variant form without parentheses gradually evolving: "4 Vesta". Other variants, including all forms of the original circled numbers, "(4)" alone, and "4, Vesta" had more or less completely died out by 1949.^[2]

One exception to the rule that the number lists order of discovery is the case of Pluto, which being initially seen as a planet was not given a number until the 2006 redefinition of "planet" that excluded it. At that point, Pluto was given the formal designation 134340 Pluto.

[edit] References

^ IAU FAQ page
^ From Dr. James Hilton's When Did the Asteroids Become Minor Planets?, particularly the discussion of Gould, B. A. 1852, On the Symbolic Notation of the Asteroids, Astronomical Journal, Vol. 2, and immediately subsequent history. The discussion of C. J. Cunningham (1988), also from there, explains the parenthetical part.