Date: August 2, 2010

Title: Solar System Nomenclature


Podcaster: Brian Gray

Organization: Wilderness Center Astronomy Club –

Description: The names of planetary features follow themes from the names of composers to the names of gods from various mythologies.

Bio: I am an amateur astronomer in northeast Ohio who enjoys viewing many types of celestial objects.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by John Cary.


Humans love to map and name landmarks. It gives us a sense of control over our surroundings. We draw imaginary lines on charts to help us locate and report about things out there. We give names to features such as mountains, craters, and valleys so we can tell each other about our environment and about what we consider to be important to us. The same is true for locations not on Earth. To avoid confusion and conflict, astronomers created conventions for naming features on other bodies in our solar system. Such objects include planets, their natural satellites, and asteroids.

Hello, my name is Brian Gray and I am a member of the Wilderness Center Astronomy Club located in Wilmot, Ohio. My club has a public star watch on the first Friday of every month. We present a planetarium show followed by observing if the weather permits. You can find details about our club and our events at .

The standard for naming features in the solar system is administered by the Working Group for Planetary System Nomenclature (WGPSN) of the International Astronomical Union. When images of a surface become available for the first time, an IAU task group will propose names of the more prominent sites and suggest a theme for any additional features that may be recorded by future imaging or mapping. Scientists or investigators involved in the imaging or describing of the additional points of interest can propose names for these landmarks but the WGPSN has to approve the name before it becomes official record in the Gazetteer of Planetary Nomenclature.

There are several categories for the general types of terrain that may be discovered. A chain of craters is a catena. A crater is of course a circular depression. A region of broken terrain is a chaos. A mare is a sea or a large circular plain. A flat-topped prominence is a mensa. A mountain is called a mons. A low plain is a planitia while a high plain or plateau is a planum. Regio is a large area with a color or albedo distinct from surrounding areas. A sinus is a bay or small plain, and a valley is called a vallis.

On Mercury, craters are named after deceased artists, musicians, painters, and authors such as Bach, Bronte, Cervantes, Dali, Giotto, and Mark Twain. A mons is named after a word for hot in some language such as Caloris. A planitia is named after Mercury in different languages. Examples include Odin and Tir. A vallis is named after a radio telescope facility such as Arecibo or Haystack.

Features on Venus are generally named after women or female deities. A deceased woman with outstanding contributions in her field may have a crater named in her honor such as Mead, Isabella, or Meitner. A planum is named after a goddess of prosperity such as Turan. Montes are usually named after goddesses such as Atanua or Var. A vallis incorporates the word for Venus in various languages such as Baltis and Citlalpul.

Craters on the Moon are named for deceased scientists, scholars, artists, and explorers such as Hertzsprung, Lorenz, and Mendeleev while maria are named after weather conditions such as Frigoris, Imbrium, and Nubium. A mons can be named after terrestrial mountains or a nearby crater such as Caucasus, Archimedes, or Alpes.

Valles on Mars are named either after the word for Mars in different languages or small rivers. Examples include Marineris, Ares, Maja, and Niger. Deceased scientists or authors that contributed to Martian lore may be honored with a large crater such as Schiaparelli, Huygens, Cassini, and Asimov. Small craters are named after small towns or villages such as Innsbruck, Valverde, and Pompeii.

Features on the Martian moon Deimos are named after authors who wrote about the Martian satellites such as Swift and Voltaire. If you are a scientist studying Martian satellites or a character from Gulliver’s Travel, you may have your name attached to something on Phobos just like Roche, Hall, or Gulliver.

On Jupiter’s moon Io, active eruptive centers are named after fire, sun, thunder, or volcano gods or heroes such as Prometheus, Masubi, and Thor. Europa has a Celtic theme with place names such as Angus, Tegid, Callanish, and Falga. Gods, heroes, and places associated with the ancient Fertile Crescent such as Uruk or Tiamat dominate the names of features on Ganymede while Callisto has names incorporating the myths of the Far North such as Valhalla and Asgard.

Orbiting Saturn, Enceladus has place names that are taken from people and places of the Arabian Nights such as Baghdad, Cairo, and Ali Baba. People and places from Homer’s Odyssey take center stage on Tethys with names like Ithaca, Odysseus, and Penelope. Maria on Titan are named after sea creatures from myth and literature such as Kracken and Punga while craters honor gods and goddesses of wisdom such as Selk.

Shakespeare rules on the moons of Uranus. Puck has mischievous
spirits like Bogle. Elsinore, Prospero, and Naples can be found on Miranda, and female characters like Ursula and Elinor can be found on Titania.

Neptune’s moon Triton has features with non-Roman and non-Greek aquatic names such as Leviathan and Kurma.

Asteroids that have been visited by spacecraft also have naming themes for their points of interest. Craters on Eros are associated with lovers in myth and legend that include Narcissus, Cupid, and Lolita. Gaspra has craters named after spas of the world such as Saratoga, Yalta, and Bath.

With the current Dawn mission heading toward Vesta and then Ceres, there will be many opportunities for the Gazetteer of Planetary Nomenclature to increase in size in the near future. A few current unofficial names will probably become confirmed and many new names will be proposed. Stay tuned. Thank you.

End of podcast:

365 Days of Astronomy
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