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seismology

(Encyclopedia)seismology sīzmŏlˈəjē, sīs– [key], scientific study of earthquakes and related phenomena, including the propagation of waves and shocks on or within the earth by natural or artificially genera...

plate tectonics

(Encyclopedia)CE5 Plate tectonics: Map of the world showing major plates and plate boundaries CE5 Plate tectonics: Schematic model of the oceanic crust, showing the three types of plate boundaries plate tect...

stratosphere

(Encyclopedia)stratosphere strătˈəsfēr [key], second lowest layer of the earth's atmosphere. The level from which it extends outward varies with latitude; it begins c.51⁄2 mi (9 km) above the poles, c.6 or 7 ...

Ptolemy

(Encyclopedia)Ptolemy (Claudius Ptolemaeus), fl. 2d cent. a.d., celebrated Greco-Egyptian mathematician, astronomer, and geographer. He made his observations in Alexandria and was the last great astronomer of ancie...

Sabbatarians

(Encyclopedia)Sabbatarians, persons who insist upon strict observance of Sunday as the Sabbath. Societies promoting Sabbatarian objectives include the Lord's Day Alliance of the United States and the Lord's Day Obs...

Idrisi

(Encyclopedia)Idrisi ĕ– [key], in full Abu Abdallah Muhammad Ibn Muhammad Ibn Abdallah Ibn Idris Al-Hammudi Al-Hasani Al-Idrisi, b. 1099?, d. after 1154, Arab geographer, b. Ceuta. He traveled in Europe, Asia Mi...

Gilbert, William

(Encyclopedia)Gilbert, William, 1544–1603, English scientist and physician. He studied medicine at Cambridge (M.D., 1569), where he was elected a Fellow of St. John's College, and set up practice in London, becom...

Orbiting Geophysical Observatory

(Encyclopedia)Orbiting Geophysical Observatory (OGO), series of six orbiting observatories (see observatory, orbiting) launched between 1964 and 1969 by the National Aeronautics and Space Administration (NASA) to s...

lithosphere

(Encyclopedia)lithosphere lĭthˈəsfērˌ [key], brittle uppermost shell of the earth, broken into a number of tectonic plates. The lithosphere consists of the heavy oceanic and lighter continental crusts, and the...

asteroid

(Encyclopedia)CE5 The asteroid belt lies between the orbits of Mars and Jupiter. Gaps where no asteroids are found are called Kirkwood gaps. The Trojan asteroids share Jupiter's orbit with the planet. asteroid,...