Gazetteer of Planetary Nomenclature
International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN)
Planetary Names: Descriptor Terms (Feature Types)

Descriptor Terms (Feature Types)

Descriptor terms are intended to represent morphological characteristics, not geological origin. The WGPSN does not endorse any specific scientific hypotheses when assigning descriptors.


Chart of landform types created in 1979 by Anne Gifford, who was then at the Air and Space Museum, Smithsonian Institution, Washington, D.C.


Feature (Designation) Description
Albedo Feature AL Geographic area distinguished by amount of reflected light
Arcus, arcūs AR Arc-shaped feature
Astrum, astra AS Radial-patterned features on Venus
Catena, catenae CA Chain of craters
Cavus, cavi CB Hollows, irregular steep-sided depressions usually in arrays or clusters
Chaos, chaoses CH Distinctive area of broken terrain
Chasma, chasmata CM A deep, elongated, steep-sided depression
Collis, colles CO Small hills or knobs
Corona, coronae CR Ovoid-shaped feature
Crater, craters AA A circular depression
Dorsum, dorsa DO Ridge
Eruptive center ER Active volcanic centers on Io
Facula, faculae FA Bright spot
Farrum, farra FR Pancake-like structure, or a row of such structures
Flexus, flexūs FE A very low curvilinear ridge with a scalloped pattern
Fluctus, fluctūs FL Flow terrain
Flumen, flumina FM Channel on Titan that might carry liquid
Fossa, fossae FO Long, narrow depression
Fretum, freta FT Strait, a narrow passage of liquid connecting two larger areas of liquid
Insula, insulae IN Island (islands), an isolated land area (or group of such areas) surrounded by, or nearly surrounded by, a liquid area (sea or lake)
Labes, labēs LA Landslide
Labyrinthus, labyrinthi LB Complex of intersecting valleys or ridges.
Lacuna, lacunae LU Irregularly shaped depression on Titan having the appearance of a dry lake bed
Lacus, lacūs LC "Lake" or small plain; on Titan, a "lake" or small, dark plain with discrete, sharp boundaries
Landing site name LF Lunar features at or near Apollo landing sites
Large ringed feature LG Cryptic ringed features
Linea, lineae LI A dark or bright elongate marking, may be curved or straight
Lingula, lingulae LN Extension of plateau having rounded lobate or tongue-like boundaries
Macula, maculae MA Dark spot, may be irregular
Mare, maria ME “Sea”; on the Moon, low albedo, relatively smooth plain, generally of large extent; on Mars, dark albedo areas of no known geological significance; on Titan, large expanses of dark materials thought to be liquid hydrocarbons
Mensa, mensae MN A flat-topped prominence with cliff-like edges
Mons, montes MO Mountain
Oceanus, oceani OC A very large dark area on the moon
Palus, paludes PA "Swamp"; small plain
Patera, paterae PE An irregular crater, or a complex one with scalloped edges
Planitia, planitiae PL Low plain
Planum, plana PM Plateau or high plain
Plume, plumes PU Cryo-volcanic features on Triton
Promontorium, promontoria PR "Cape"; headland promontoria
Regio, regiones RE A large area marked by reflectivity or color distinctions from adjacent areas, or a broad geographic region
Reticulum, reticula RT reticular (netlike) pattern on Venus
Rima, rimae RI Fissure
Rupes, rupēs RU Scarp
Satellite Feature SF A feature that shares the name of an associated feature. For example, on the Moon the craters referred to as "Lettered Craters" are classified in the gazetteer as "Satellite Features."
Saxum, saxa SA Boulder or rock
Scopulus, scopuli SC Lobate or irregular scarp
Serpens, serpentes SE Sinuous feature with segments of positive and negative relief along its length
Sinus, sinūs SI "Bay"; small plain; on Titan, bays within seas or lakes of liquid hydrocarbons
Sulcus, sulci SU Subparallel furrows and ridges
Terra, terrae TA Extensive land mass
Tessera, tesserae TE Tile-like, polygonal terrain
Tholus, tholi TH Small domical mountain or hill
Unda, undae UN Dunes
Vallis, valles VA Valley
Vastitas, vastitates VS Extensive plain
Virga, virgae VI A streak or stripe of color