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crucible

(Encyclopedia)crucible, vessel in which a substance is heated to a high temperature, as for fusing or calcining. The necessary properties of a crucible are that it maintain its mechanical strength and rigidity at h...

color index

(Encyclopedia)color index, in astronomy, difference in an object's brightness as recorded between any two well-defined bands of the electromagnetic spectrum by using optical filters of different colors. If blue and...

Challenger

(Encyclopedia)Challenger, U.S. space shuttle. It exploded (Jan. 28, 1986) 73 seconds into its tenth flight, killing all seven crew members, including the first civilian in space, schoolteacher Christa McAuliffe. Th...

house plants

(Encyclopedia)house plants, varied group of plants grown indoors and requiring no special care. They are usually grown singly in pots, but can also be grouped and planted together in dish gardens and terrariums. So...

analog circuit

(Encyclopedia)analog circuit, electronic circuit that operates with currents and voltages that vary continuously with time and have no abrupt transitions between levels. Generally speaking, analog circuits are cont...

neoteny

(Encyclopedia)neoteny nēŏtˈənē [key], in biology, sexual maturity reached in the larval stage of some animals. Certain environmental conditions can inhibit the completion of metamorphosis; low temperature or l...

kiln

(Encyclopedia)kiln kĭl, kĭln [key], furnace for firing pottery and enamels, for making brick, charcoal, lime, and cement, for roasting ores, and for drying various substances (e.g., lumber, chemicals). Kilns may ...

catchment area

(Encyclopedia)catchment area or drainage basin, area drained by a stream or other body of water. The limits of a given catchment area are the heights of land—often called drainage divides, or watersheds—separat...

Spectral Classes for Main Sequence Stars (table)

(Encyclopedia)Characteristics of Spectral Classes for Main Sequence Stars ...

timberline

(Encyclopedia)timberline, elevation above which trees cannot grow. Its location is influenced by the various factors that determine temperature, including latitude, prevailing wind directions, and exposure to sunli...