Steven Dutch, Natural and Applied Sciences, University
of Wisconsin - Green Bay
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Early observers thought the dark plains on the Moon were seas and lakes and gave them names like Mare Tranquillitatis (Sea of Tranquillity, where Apollo 11 landed). We retain those traditional names even though, of course, we know they are not seas.
In the 1600's, the Italian astronomer Giovanni Riccioli began the custom of naming craters on the Moon for great astronomers. A large crater was later named for Riccioli himself. There's almost a perverse, inverse relationship between the size of a crater and the astronomer's contribution to lunar studies. Great as Plato, Tycho, and Copernicus are, they did not advance our understanding of the Moon much, but they have some of the largest and most conspicuous craters named for them. (By the time telescopes were powerful enough to allow serious research on the Moon, all the good craters were taken!)
Planetary probes revealed that there are far more craters than astronomers, great and otherwise, so names of objects on other planets are derived from other biographical categories or mythology. A commission of the International Astronomical Union oversees naming, and the names (so far) are recognized by the various spacefaring nations. The rules are:
Planetary geographical features have Latin names. Latin is traditional, apolitical, and the closest thing to a universal language in history. The following are in use, with the literal Latin translation in parentheses, followed by the geographical meaning.
Catena (Chain) Chain of small craters
Cavus (Hollow) Steep-walled pit
Chaos (Chaos) Extremely irregular terrain
Chasma (Gorge, Chasm) Long, deep valley or rift
Dorsum (Spine) Ridge
Fossa (Trench) Shallow fissure
Labyrinthus (Maze) Complex network of channels
Lacus (Lake) Small lava plain. Used only on Moon
Linea (Line) Line or band
Macula (Spot) Dark spot (im-macula-te means "spotless")
Mare (Sea) Large lava plain. Used only on Moon
Mensa (Table) Flat-topped hill, mesa, table-land
Mons (Mountain) Mountain, plural Montes
Oceanus (Ocean) Large lava plain. Used only on Moon
Palus (Swamp) Small lava plain. Used only on Moon
Patera (Saucer) Volcanic crater or caldera
Planitia (Plain) Low plain, basin
Planum (Plain) Plateau
Regio (Region) Region
Rima (Crack) Small fissure
Rupes (Cliff) Cliff or scarp
Scopulus (Crag, Ledge) Irregular scarp
Sinus (Bay) Embayment. Used on Moon, Mars
Sulcus (Furrow) Network of parallel ridges and grooves
Terra (Land) Continent-sized land mass
Tholus (Shield) Dome, usually volcanic
Vallis (Valley) Valley
Vastitas (Wasteland) Large plain
Australis, Meridionalis - South
Borealis, Septentrionalis - North
The U.S. Geological Survey site, Gazetteer of Planetary Nomenclature, gives a complete listing of naming conventions.
Inventor of the lyre in Greek mythology, hence craters named for great figures in the arts. Large regions are named for deities equivalent to Mercury.
Female figures in history and mythology
Some traditional names were given by Earth-based observers. Some large craters named for famous scientists. Small craters named for cities and towns on Earth
Uranus is the only body in the Solar System with moons not named from classical mythology - its moons are named from works by Shakespeare and Alexander Pope. Any future satellites will follow that naming convention.
Neptune, god of the sea, has satellites named for minor deities connected with sea myths. Features on Triton have aquatic names.
Features on Pluto will be drawn from underworld myths.
Names of minor planets rapidly ran out of mythological characters and now include cities, observatories, people (the dead Challenger and Columbia astronauts among them) and many other things. The minor planets with named features typically follow some theme associated with the name of the minor planet itself. Gaspra, named after a European spa, has craters named after spas, and so on. Having some class of features named after people involved in mapping the body is also common. Eros, named after the god of love, will have craters named after famous erotic figures. Before you nominate yourself, bear in mind that features cannot be named after living people.
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Created 20 May 1997, Last Update 1 November 1999
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