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earth, in geology and astronomy

From The Columbia Encyclopedia
in geology and astronomy, 3rd planet of the solar system and the 5th largest, the only planet definitely known to support life. Gravitational forces have molded the earth, like all celestial bodies, into a spherical shape. However, the earth is not an exact sphere, being slightly flattened at the poles and bulging at the equator. The equatorial diameter is c.7,926 mi (12,760 km) and the polar diameter 7,900 mi (12,720 km); the circumference at the equator is c.24,830 mi (40,000 km). The surface of the earth is divided into dry land and oceans, the dry land occupying c.57.5 million sq mi (148.9 million sq km), and the oceans c.139.5 million sq mi (361.3 million sq km). The earth is surrounded by an envelope of gases called the atmosphere, of which the greater part is nitrogen and oxygen. Knowledge of the earth's interior has been gathered by three methods: by the analysis of earthquake waves passing through the earth (see seismology ), by analogy with the composition of meteorites, and…
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Full text Article Earth

From Astronomy Encyclopedia
Earth En route to the Moon in 1972 December, the...
Third planet from the Sun; the largest and most massive of the four TERRESTRIAL PLANETS and the only planet known to support life. Its mean distance from the Sun is defined as one ASTRONOMICAL UNIT , a convenient standard for the description of distances within the Solar System. Its orbit around the…
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Full text Article earth

From Chambers Dictionary of the Unexplained
One of the four elements believed in ancient and medieval cosmology to be the fundamental components of all things; of prime importance in magic and the occult. In ancient and medieval philosophy and alchemy, all things were believed to be composed of a blend of four classical elements : air , water…
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Full text Article Earth

From Philip's Encyclopedia
The Earth formed c.4,600 million years ago. The...
Third major planet from the Sun, and the largest of the four inner, terrestrial planets. Water covers c .70% of the Earth's surface, at which the average temperature is 13°C (55°F). Continental land masses make up the other 30%. Earth has one natural satellite, the Moon . The dense core , rich in…
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Earthquake epicentres, shown as...
The philosophers of Ancient Greece proposed various ideas about the configuration of the Earth. The Pythagoreans of about 500 BC were probably the first to appreciate that the Earth is spherical. And around a hundred years later Hicetas of Syracuse seems to have been the first to conclude that the…
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Full text Article EARTH

From Gaither's Dictionary of Scientific Quotations
American environmentalist and nature writer We know so very little about this strange planet we live on, this haunted world where all answers lead only to more mystery. The Crooked Word Audubon Magazine, Volume 77 , Number 6 , 1975 (p. 24 ). We are obliged, therefore, to spread the news, painful ... …
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Full text Article earth

From The Chambers Dictionary
the third planet in order from the sun (often with cap ); the material on the surface of the globe; soil, a mixture of disintegrated rock and organic material, in which plants are rooted; dry land as opposed to sea; the land and sea as opposed to the sky; the world; the inhabitants of the world; …
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Full text Article earth

From The Macquarie Dictionary
the planet which we inhabit, the third in order from the sun. Its period of revolution is 1 year, and its mean distance from the sun 149 597 870 km. Its diameter is 12 756 km. It has one satellite, the moon. Plural: earths noun /30/ /erth/ the inhabitants of this planet the whole earth rejoiced., …
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Full text Article Earth

From Brewer's Dictionary of Phrase and Fable
It was a popular medieval belief that Paradise, a land or island where everything was beautiful and restful, and where death and decay were unknown, still existed somewhere on earth. It was usually located far away to the East, and in 9th-century maps it is shown in China. The fictitious letter of…
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Full text Article Earth

From Britannica Concise Encyclopedia
Earth’s interior may be identified in two...
Third planet in distance outward from the Sun . Believed to be about 4.56 billion years old, it is some 149,600,000 km (92,960,000 mi) from the Sun. It makes one revolution, or one complete orbit of the Sun, in about 365.25 days. As it revolves, it rotates on its axis once every 23 hours 56 minutes…
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Full text Article earth

From The American Heritage(R) Dictionary of the English Language
earth cutaway of the earth Thom Gillis TG
a. The land surface of the world. b. The softer, friable part of land; soil, especially productive soil. often Earth The third planet from the sun, having a sidereal period of revolution about the sun of 365.26 days at a mean distance of approximately 149.6 million kilometers (92.96 million miles), …
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