Lunar Atlas

Lunar Geology

Phases of
the Moon

Ice on the Moon



"Use of the prefix "geo-" for lunar and planetary studies has been criticized, but it is justified by:

  1. applicability to all other solid bodies of the geologic principles developed for the Earth;

  2. elimination of the need for new terms for every new world observed at geologically useful scales, whose number now exceeds 20;

  3. the Greek etymology, which includes the meanings "land" or "ground"

  4. three decades of usage (Shoemaker, 1962a, p 117; Ronca, 1965; Mutch,1970; Wilhelms, 1970b).

The prefix "seleno-" is no longer used by professional lunar scientists except in some terms referring to coordinates, control points, or the global figure (selenographic, selenodetic). Although "astrogeology" was chosen as a convenient and appropriate name (Milton, 1969) for the U.S Geological Survey's branch devoted to Lunar and Planetary studies, "lunar (planetary) geology" is more commonly used. "Planetology" is a broader term that includes such nongeologic sciences as atmospherics and planetary astronomy."

Text from the Geologic History of the Moon, Wilhelms, Don E., USGS professional paper 1348.

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