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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...

cycle

(Encyclopedia)cycle, in astronomy, period of time required for the recurrence of some celestial event. The length of a cycle may be measured relative to the sun or to the fixed stars (see sidereal time). A frequent...

synodic period

(Encyclopedia)synodic period sĭnŏdˈĭk [key], in astronomy, length of time during which a body in the solar system makes one orbit of the sun relative to the earth, i.e., returns to the same elongation. Because ...

rock carvings and paintings

(Encyclopedia)rock carvings and paintings, designs inscribed on rock surfaces and huge stone monuments in many parts of the world by prehistoric or preindustrial peoples. They have been found on every continent and...

In

(Encyclopedia)In, symbol for the element indium. ...

science

(Encyclopedia)science [Lat. scientia=knowledge]. For many the term science refers to the organized body of knowledge concerning the physical world, both animate and inanimate, but a proper definition would also hav...

zenith

(Encyclopedia)zenith, in astronomy, the point in the sky directly overhead; more precisely, it is the point at which the celestial sphere is intersected by an upward extension of a plumb line from the observer's lo...

William and Mary in Virginia, College of

(Encyclopedia)William and Mary in Virginia, College of, mainly at Williamsburg; state supported; coeducational; chartered 1693, opened 1694 by Episcopalians under James Blair. It became a university in 1779. The se...

Organization for Security and Cooperation in Europe

(Encyclopedia)Organization for Security and Cooperation in Europe (OSCE), international organization established as the Conference on Security and Cooperation in Europe (CSCE) in 1973, during the cold war, to promo...

node

(Encyclopedia)node, in astronomy, point at which the orbit of a body crosses a reference plane. One reference plane that is often used is the plane of the earth's orbit around the sun (ecliptic). Since the moon's o...