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Ptolemaic system

(Encyclopedia)Ptolemaic system tŏlˌəmāˈĭk [key], historically the most influential of the geocentric cosmological theories, i.e., theories that placed the earth motionless at the center of the universe with a...

Trojan asteroids

(Encyclopedia)Trojan asteroids, asteroids that revolve about the sun in the same orbit as a planet, occupying stable positions (known as Lagrangian points) either about 60° ahead of the planet in the orbit or abou...

Quirinus

(Encyclopedia)Quirinus kwĭrˈĭnəs [key], in Roman religion, an early god, possibly of war. Worshiped originally by the Sabines, he was one of the chief gods of ancient Rome, associated with Jupiter and Mars. In ...

evening star

(Encyclopedia)evening star or morning star, planet that becomes visible in the western sky shortly after sunset or in the eastern sky shortly before sunrise. It can usually be seen in twilight, when it is too light...

exobiology

(Encyclopedia)exobiology or astrobiology, search for extraterrestrial life within the solar system and throughout the universe. Philosophical speculation that there might be other worlds similar to ours dates back ...

Low, Frank James

(Encyclopedia)Low, Frank James, 1933–2009, American astronomer and physicist, b. Mobile, Ala., grad. Yale (B.S. 1955), Rice Univ. (M.A. 1957, Ph.D 1959). Low, who worked at Texas Instruments and the National Radi...

month

(Encyclopedia)month, in chronology, the conventional period of a lunation, i.e., passage of the moon through all its phases. It is usually computed at approximately 29 or 30 days. For the computation of the month a...

Möbius, Augustus Ferdinand

(Encyclopedia)Möbius, Augustus Ferdinand mōˈbēəs, Ger. möˈbēəs [key],(1790–1868), German mathematician and astronomer, b. Schulpforta, Saxony. A professor of astronomy at the Univ. of Leipzig, he made im...

Eiffel Tower

(Encyclopedia)Eiffel Tower, structure designed by A. G. Eiffel and erected in the Champ-de-Mars for the Paris exposition of 1889. The tower is 984 ft (300 m) high and consists of an iron framework supported on four...

astrometry

(Encyclopedia)astrometry: see astronomy.