Planetary nomenclature

Lore & Background

When images are first obtained of a planet or satellite, a theme for naming features is chosen and a few important features are named, usually by members of the appropriate IAU task group. Later, as higher resolution images and maps become available, additional features are named at the request of investigators mapping or describing specific surfaces, features, or geologic formations. Anyone may suggest a name; if the task group agrees it is appropriate, it can be retained for use when a request comes from a member of the scientific community. Names that pass review by a task group are submitted to the WGPSN, and once approved they are considered official, usable on maps and in publications, and listed in the Gazetteer of Planetary Nomenclature.

Names adopted by the IAU must follow rules and conventions established and amended through the years. Nomenclature should be simple, clear, and unambiguous. Official names are generally not given to features smaller than 100 meters, except for those of exceptional scientific interest. The number of names per body should be kept to a minimum, and duplication of the same name on two or more bodies is discouraged. Names should be expressed in the language of origin, with transliteration for various alphabets but no translation. Solar system nomenclature should be international, with an equitable selection of names from ethnic groups, countries, and gender on each map. No names having political, military, or modern religious significance may be used, except for political figures prior to the 19th century. Commemoration of persons is reserved for those of high and enduring international standing, deceased for at least three years.

Reader's Guide

The IAU's planetary nomenclature system provides a standardized, internationally recognized method for naming features on Solar System bodies, ensuring clarity and consistency for scientific and cartographic communities. The approval procedure involves task groups, the WGPSN, and final IAU approval, with any person able to suggest names. The rules emphasize simplicity, international character, and avoidance of duplication or political/religious significance. The system includes descriptor terms for feature types (e.g., craters have an implicit descriptor), and conventions vary by body—for example, all but three features on Venus are named after female personages, while features on Deimos are named after authors who wrote about Martian satellites. The system also allows for informal names during active missions, but these are not given official status unless they meet established rules. The IAU's framework has been used to name features across the Solar System, from Mercury to satellites of Uranus, with themes drawn from mythology, literature, and science. The Gazetteer of Planetary Nomenclature serves as the official repository of approved names.

Did You Know?

• All but three features on Venus are named after female personages; the exceptions are Alpha Regio, Beta Regio, and Maxwell Montes.
• Features on Deimos are named after authors who wrote about Martian satellites, with currently two named features: Swift crater and Voltaire crater.