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Eris, in astronomy

(Encyclopedia)Eris, in astronomy, the largest known dwarf planet. Eris, whose highly eccentric elliptical orbit ranges from 38 AU to 97 AU and is inclined more than 44°, is the largest known object of the Kuiper b...

Sedna

(Encyclopedia)Sedna, in astronomy, the most distant known large object in the solar system. With a highly eccentric elliptical orbit that ranges from an estimated 76 AU to 937 AU, Sedna also has an extremely long o...

Olbers, Heinrich Wilhelm Matthäus

(Encyclopedia)Olbers, Heinrich Wilhelm Matthäus hīnˈrĭkh vĭlˈhĕlm mätĕˈo͝os ôlˈbərs [key], 1758–1840, German astronomer and physician. He originated (1797) the first satisfactory method for calculat...

European Space Agency

(Encyclopedia)European Space Agency (ESA), multinational agency dedicated to the promotion, for exclusively peaceful purposes, of cooperation among European states in space research and technology. Member states in...

Tombaugh, Clyde William

(Encyclopedia)Tombaugh, Clyde William tŏmˈbô [key], 1906–97, American astronomer, b. Streator, Ill. Although lacking formal training or a college degree, he was hired in 1929 as an assistant by the Lowell Obse...

Oort, Jan Hendrik

(Encyclopedia)Oort, Jan Hendrik ōrt [key], 1900–1992, Dutch astronomer. He confirmed (1927) Bertil Lindblad's theory of the Milky Way galaxy's rotation. In the 1950s he and his colleagues used radio astronomical...

Whipple, Fred Lawrence

(Encyclopedia)Whipple, Fred Lawrence, 1906–2004, American astronomer, b. Red Oak, Iowa. After graduating from the Univ. of California, Berkeley (Ph.D. 1931), he accepted a position at Harvard, where he remained f...

Royal Greenwich Observatory

(Encyclopedia)Royal Greenwich Observatory, astronomical observatory established in 1675 by Charles II of England at Greenwich and known as the Royal Observatory. It moved during 1948–57 to Herstmonceux Castle, Su...

ephemeris

(Encyclopedia)ephemeris ĭfĕmˈərĭs [key] (pl., ephemerides), table listing the position of one or more celestial bodies for each day of the year. The French publication Connaissance de Temps is the oldest of th...

solar wind

(Encyclopedia)solar wind, stream of ionized hydrogen—protons and electrons—with an 8% component of helium ions and trace amounts of heavier ions that radiates outward from the sun at high speeds. The continuous...

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