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galaxy

(Encyclopedia)CE5 Hubble classification of galaxies: Elliptical galaxies (E) are classified according to the degree of flattening of the ellipse. Spiral galaxies (S) and barred spiral galaxies (SB) are classifie...

observatory, orbiting

(Encyclopedia)observatory, orbiting, research satellite designed to study solar radiation, electromagnetic radiation from distant stars, the earth's atmosphere, or the like. Because the atmosphere and other aspects...

Michigan, Lake

(Encyclopedia)Michigan, Lake, 22,178 sq mi (57,441 sq km), 307 mi (494 km) long and 30 to 120 mi (48–193 km) wide, bordered by Mich., Ind., Ill., and Wis.; third largest of the Great Lakes and the only one entire...

atomic clock

(Encyclopedia)atomic clock, electric or electronic timekeeping device that is controlled by atomic or molecular oscillations. A timekeeping device must contain or be connected to some apparatus that oscillates at a...

madder

(Encyclopedia)CE5 Bluet, Houstonia caerulea, a member of the madder family madder, common name for the Rubiaceae, a family of chiefly tropical and subtropical trees, shrubs, and herbs, especially abundant in N ...

plutonium

(Encyclopedia)plutonium plo͞otōˈnēəm [key], radioactive chemical element; symbol Pu; at. no. 94; mass no. of most stable isotope 244; m.p. 641℃; b.p. 3,232℃; sp. gr. 19.84 at 20℃; valence +3, +4, +5, or ...

space exploration

(Encyclopedia)CE5 Moon mission assembly CE5 Stages in a moon mission shown counterclockwise from launching on the first day to splashdown on the ninth day. space exploration, the investigation of physical co...

Uranus , in astronomy

(Encyclopedia)Uranus yo͝orāˈnəs, yo͝orˈə– [key], in astronomy, 7th planet from the sun, at a mean distance of 1.78 billion mi (2.87 billion km), with an orbit lying between those of Saturn and Neptune; its...

hurricane

(Encyclopedia)CE5 View into the eye of a hurricane showing the structure of the surrounding cloud wall hurricane, tropical cyclone in which winds attain speeds greater than 74 mi (119 km) per hr. Wind speeds gu...

concrete

(Encyclopedia)concrete, structural masonry material made by mixing broken stone or gravel with sand, cement, and water and allowing the mixture to harden into a solid mass. The cement is the chemically active eleme...