Celestial nomenclature has long been a controversial topic. At its inaugural meeting in 1922 in Rome, the IAU standardized the constellation names and abbreviations. More recently IAU Committees or Working Groups have certified the names of astronomical objects and features. In the following links you can find further information on how different objects and features are named.



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Spelling of Names

Questions have been asked about the proper English spelling of names of astronomical objects, especially as regards capitalization of such names.

The IAU formally recommends that the initial letters of the names of individual astronomical objects should be printed as capitals (see the IAU Style Manual, Trans. Int. Astron. Union, volume 20B, 1989; Chapter 8, page S30 – PDF file); e.g., Earth, Sun, Moon, etc. "The Earth's equator" and "Earth is a planet in the Solar System" are examples of correct spelling according to these rules.

It is emphasized, however, that language conventions are the responsibility of individual nations or groups of nations. While the IAU is willing to help to achieve a minimum degree of orthographic consistency as regards astronomical terms, it cannot undertake to do so for all languages, nor is it in the power of the IAU to enforce the application of any such conventions.

If a name is difficult to spell or pronounce, it may not be the best choice for use on maps and in presentations. Sometimes multi-word names are discouraged for this reason. The purpose of nomenclature is to provide simple, clear, unambiguous names for features.

Naming of Solar System Objects and Features

The IAU has been the arbiter of planetary and satellite nomenclature since its inception in 1919 (also see Resolution 13 of the Fourth United Nations Conference on the Standardization of Geographical Names, held in Geneva in 1982). The various IAU Working Groups normally handle this process, and their decisions primarily affect the professional astronomers. But from time to time the IAU takes decisions and makes recommendations on issues concerning astronomical matters affecting other sciences or the public. Such decisions and recommendations are not enforceable by any national or international law; rather they establish conventions that are meant to help our understanding of astronomical objects and processes. Hence, IAU recommendations should rest on well-established scientific facts and have a broad consensus in the community concerned.

Major Planets and the Moon

The eight major planets in our Solar System and Earth's satellite have official IAU names. The names of the major planets were already in common use when the IAU formed in 1919 (e.g. scientifically, in professional and amateur astronomy literature, in nautical almanacs, etc.). However, the names of the planets have been included in wording for IAU resolutions multiple times since the IAU's founding and these names can be considered formally adopted by the IAU membership. While there are cultural names for the planets and Earth's satellite in other languages, there are classic names for the major planets and Moon which appear in English language IAU resolutions and the IAU Style Manual (which was approved by an IAU resolution in 1988).

What follows is a partial list of instances of use of these planet names, but it is by no means exhaustive. This compilation demonstrates, however, that the names of the planets and Moon have appeared in IAU resolutions (or in wording of documents approved by IAU resolution) approved by IAU General Assemblies multiple times, and continue to be in ubiquitous use.

1976: The names of the then major planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto) and the Earth's satellite (Moon) appear in IAU Resolution No. 10, which was approved by the XVIth General Assembly of the IAU in Grenoble, France in 1976.

1988: The IAU XXth General Assembly — which met in Baltimore in 1988 — approved IAU Resolution A3 on the Improvement of Publications, which recognized "the importance of identifying astronomical objects by clear and unambiguous designations" and recommended "that the authors and editors of the astronomical literature adopt the recommendations in the IAU Style Manual". The "IAU Style Manual (1989): The Preparation of Astronomical Papers and Reports" by George A. Wilkins (President of IAU Commission 5) was published in December 1988, and reprinted as Chapter VIII ("IAU Style Book") in the "Transactions of the International Astronomical Union Vol. XXB: Proceedings of the Twentieth General Assembly Baltimore 1988" (1990; ed. Derek McNally; Kluwer Academic Publishers; Dordrecht). The IAU Style Manual Sec. 5.25 lists the names of the "principal planets" as Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.

2006: IAU Resolution B5 (Definition of a Planet in the Solar System) explicitly lists the eight planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. While Resolution B5 defined the category of dwarf planet, Resolution B6 explicitly lists Pluto as an example.

One also sees these planet names are used ubiquitously by modern IAU working groups (e.g. IAU Working Group for Planetary System Nomenclature, the IAU Working Group on Cartographic Coordinates and Rotational Elements in their recent report by Archinal et al. 2011 Celestial Mechanics and Dynamical Astronomy, Vol. 109, Issue 2, pp. 101-135, etc.).

So the IAU does recognize official names for the major planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune) and Earth's satellite (Moon).

Planetary Features

Planetary nomenclature, like terrestrial nomenclature, is used to uniquely identify a feature on the surface of a planet or satellite so that the feature can be easily located, described, and discussed. The procedure is as follows:

When the first images of the surface of a planet or satellite are obtained, themes for naming features are chosen and names of a few important features are proposed, usually by members of the appropriate IAU task group.

As higher resolution images and maps become available, names for additional features may be requested by investigators mapping or describing specific surfaces or geological formations.

At this point, anyone may suggest that a specific name be considered by a Task Group, but there is no guarantee that the name will be accepted. Please submit name requests via this form.

Names successfully reviewed by a task group are submitted by the task group chair to the Working Group for Planetary System Nomenclature (WGPSN).

Upon successful review by vote of the members of the WGPSN, names are considered approved as official IAU nomenclature, and can be used on maps and in publications. Approved names are immediately entered into the Gazetteer of Planetary Nomenclature, and posted on its web site. Any objections to these names based on significant substantive problems or inconsistent application of normal IAU naming convention must be forwarded in writing or email to the IAU General-Secretary within three months from the time the name was placed on the web site. The General-Secretary will make a recommendation to the WGPSN Chair as to whether or not the approved name(s) should be reconsidered. The General-Secretary, in concurrence with the IAU President, may seek the advice of external consultants.

Approved names are also listed in the transactions of the IAU.

The categories of the planetary features are listed here.

(from http://planetarynames.wr.usgs.gov/approved.html)