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National Science Foundation

(Encyclopedia)National Science Foundation (NSF), an independent agency in the executive branch of the U.S. federal government concerned with promoting a national science policy by supporting basic research and educ...

culminate

(Encyclopedia)culminate, in astronomy, the maximum height in the sky reached by a celestial body on a given day. At the culminate the body is crossing the observer's celestial meridian and is said to be in upper tr...

Tereshkova, Valentina Vladimirovna

(Encyclopedia)Tereshkova, Valentina Vladimirovna, 1937–, Soviet cosmonaut. She was the first woman to orbit the earth, in Vostok 6 on June 16–19, 1963. She left the Soviet space program soon after and married c...

Nut, in Egyptian religion

(Encyclopedia)Nut no͝ot, nŭt [key], in Egyptian religion, sky-goddess. She was the sister-wife of the earth god Geb, to whom she bore Osiris, Isis, Set, and Nephthys. She was sometimes represented with her hands ...

sidereal period

(Encyclopedia)sidereal period, in astronomy, length of time a body takes to complete an orbit relative to the fixed stars. See sidereal time. ...

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...

linden, in botany

(Encyclopedia)CE5 Linden, Tilia americana linden, common name for the Tiliaceae, a family of chiefly woody shrubs and trees. Most genera are tropical, but the genus Tilia, commonly called linden, or lime tree, ...

lens, in optics

(Encyclopedia)CE5 Lenses lens, device for forming an image of an object by the refraction of light. In its simplest form it is a disk of transparent substance, commonly glass, with its two surfaces curved or wi...

larkspur, in botany

(Encyclopedia)larkspur, any north temperate, Old World annual of the genus Consolida of the buttercup family. Consolida species were formerly classified in the genus Delphinium, which includes similar annual, bienn...

larva, in zoology

(Encyclopedia)larva, independent, immature animal that undergoes a profound change, or metamorphosis, to assume the typical adult form. Larvae occur in almost all of the animal phyla; because most are tiny or micro...