Planetary geology

Planetary geologist and NASA astronaut Harrison "Jack" Schmitt collecting lunar samples during the Apollo 17 mission in early-December 1972

Surface of Mars as photographed by the Viking 2 lander December 9, 1977.

ESA Huygens in situ image from Titan's surface—the only image from the surface of a body farther away than Mars

Same image with contrast enhanced

Planetary geology, alternatively known as astrogeology or exogeology, is a planetary science discipline concerned with the geology of the celestial bodies such as the planets and their moons, asteroids, comets, and meteorites.^[1][2] Although the geo- prefix typically indicates topics of or relating to the Earth, planetary geology is named as such for historical and convenience reasons; applying geological science to other planetary bodies. Due to the types of investigations involved, it is also closely linked with Earth-based geology.

Planetary geology includes such topics as determining the internal structure of the terrestrial planets, and also looks at planetary volcanism and surface processes such as impact craters, fluvial and aeolian processes. The structures of the giant planets and their moons are also examined, as is the make-up of the minor bodies of the Solar System, such as asteroids, the Kuiper Belt, and comets.

History of planetary geology

Eugene Shoemaker is credited with bringing geologic principles to planetary mapping and creating the branch of planetary science in the early 1960s, the Astrogeology Research Program, within the United States Geological Survey. He made important contributions to the field and the study of impact craters, Selenography (study of the Moon), asteroids, and comets.^[3]

Today many institutions are concerned with the study and communication of planetary sciences and planetary geology. The Visitor Center at Barringer Meteor Crater near Winslow, Arizona includes a Museum of planetary geology. The Geological Society of America's Planetary Geology Division has been growing and thriving since May 1981 and has two mottos: "One planet just isn't enough!" and "“The GSA Division with the biggest field area!"

Major centers for planetary science research include the Lunar and Planetary Institute, the Applied Physics Laboratory, the Planetary Science Institute, the Jet Propulsion Laboratory, Southwest Research Institute, and Johnson Space Center. Additionally, several universities conduct extensive planetary science research, including Montana State University, Brown University, the University of Arizona, Caltech, the University of Colorado, Western Michigan University, MIT, and Washington University in St. Louis.

Features and terms

Planetary geology uses a wide variety of standardised descriptor names for features.^[4] All planetary feature names recognised by the International Astronomical Union combine one of these names with a possibly unique identifying name. The conventions which decide the more precise name are dependent on which planetary body the feature is on, but the standard descriptors are in general common to all astronomical planetary bodies. Some names have a long history of historical usage, but new must be recognised by the IAU Working Group for Planetary System Nomenclature as features are mapped and described by new planetary missions.^[5] This means that in some cases names may change as new imagery becomes available,^[5] or in other cases widely adopted informal names changed in line with the rules.^[6] The standard names are chosen to consciously avoid interpreting the underlying cause of the feature, but rather to describe only its appearance.^[4]

By planet

References

Further reading

• J. F. Bell III; B. A. Campbell; M. S. Robinson (2004). Remote Sensing for the Earth Sciences: Manual of Remote Sensing (3rd ed.). John Wiley & Sons. Retrieved 2006-08-23.
• Roberge, Aki (1998-04-21). "The Planets After Formation". Department of Terrestrial Magnetism. Archived from the original on 2006-08-13. Retrieved 2006-08-23.