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isotherm

(Encyclopedia)isotherm, line drawn on a map of a particular region of the earth's surface connecting points of equal temperature; each point reflects one temperature reading or an average of several readings over a...

Philemon and Baucis

(Encyclopedia)Philemon and Baucis, in Greek mythology, Phrygian husband and wife. When Zeus and Hermes visited earth as men, only Philemon and Baucis offered them hospitality. As a reward they were saved from a pun...

lava

(Encyclopedia)lava läˈvə [key], molten rock that erupts on the earth's surface, either on land or under the ocean, by a volcano or through a fissure. It solidifies into igneous rock that is also called lava. Bef...

Ash Wednesday

(Encyclopedia)Ash Wednesday, in the Western Church, the first day of Lent, being the seventh Wednesday before Easter. On this day ashes are placed on the foreheads of the faithful to remind them of death, of the so...

Tellus

(Encyclopedia)Tellus tĕlˈəs [key], in Roman religion, earth goddess; also called Terra Mater. As a goddess of fertility, she was worshiped at festivals held in January (in conjunction with Ceres) and in April. T...

Cleomedes

(Encyclopedia)Cleomedes klēˌōmēˈdēz, klēˌə– [key], fl. 2d cent., Greek astronomer. In a treatise on the circular theory of heavenly bodies, he recorded several hypotheses, e.g., the earth's spherical for...

reconnaissance satellite

(Encyclopedia)reconnaissance satellite, artificial satellite launched by a country to provide intelligence information on the military activities of foreign countries. There are four major types. Early-warning sate...

ecliptic

(Encyclopedia)ecliptic ēklĭpˈtĭk, ĭ– [key], the great circle on the celestial sphere that lies in the plane of the earth's orbit (called the plane of the ecliptic). Because of the earth's yearly revolution a...

elongation

(Encyclopedia)elongation, in astronomy, the angular distance between two points in the sky as measured from a third point. The elongation of a planet is usually measured as the angular distance from the sun to the ...

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