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paleomagnetism

(Encyclopedia)paleomagnetism, study of the intensity and orientation of the earth's magnetic field as preserved in the magnetic orientation of certain minerals found in rocks formed throughout geologic time. Paleom...

earthquake

(Encyclopedia)CE5 Worldwide pattern of earthquake activity: The dots indicate the epicenters of all earthquakes recorded during a recent 10-year period. CE5 earthquake, trembling or shaking movement of the ea...

environmentalism

(Encyclopedia)environmentalism, movement to protect the quality and continuity of life through conservation of natural resources, prevention of pollution, and control of land use. The philosophical foundations for ...

magnetic pole

(Encyclopedia)magnetic pole, the two roughly opposite ends of the planet where the earth's magnetic intensity is the greatest, as the north and south magnetic poles. For the magnetic north, it is the direction from...

longitude

(Encyclopedia)longitude lŏnˈjĭto͞odˌ [key], angular distance on the earth's surface measured along any latitude line such as the equator east or west of the prime meridian. A meridian of longitude is an imagin...

space science

(Encyclopedia)space science, body of scientific knowledge as it relates to space exploration; it is sometimes also called astronautics. Space science draws on the conventional sciences of physics, chemistry, biolog...

asthenosphere

(Encyclopedia)asthenosphere ăsthēnˈəsfēr [key], region in the upper mantle of the earth's interior, characterized by low-density, semiplastic (or partially molten) rock material chemically similar to the overl...

radar astronomy

(Encyclopedia)radar astronomy, application of radar to the determination of distances and planetary features within the solar system, such as rotation rates. A short burst of radio waves is transmitted in the direc...

apogee

(Encyclopedia)apogee ăpˈəjē [key], point farthest from the earth in the orbit of a body about the earth. See apsis. ...

perigee

(Encyclopedia)perigee pĕrˈĭjē [key], point nearest the earth in the orbit of a body about the earth. See apsis. ...