Planetary nebula — A planetary nebula is an emission nebula consisting of a glowing shell of gas and plasma formed by certain types of stars when they die. The name originated in the 18th century because of their similarity in appearance to giant planets when… … Wikipedia
Evaporative cooler — An evaporative cooler, photographed in Rocky Ford, Colorado, used in the drier parts of the American West to provide economical cooling … Wikipedia
steel — steellike, adj. /steel/, n. 1. any of various modified forms of iron, artificially produced, having a carbon content less than that of pig iron and more than that of wrought iron, and having qualities of hardness, elasticity, and strength varying … Universalium
climate — /kluy mit/, n. 1. the composite or generally prevailing weather conditions of a region, as temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds, throughout the year, averaged over a series of years. 2. a region or… … Universalium
star — starless, adj. /stahr/, n., adj., v., starred, starring. n. 1. any of the heavenly bodies, except the moon, appearing as fixed luminous points in the sky at night. 2. Astron. any of the large, self luminous, heavenly bodies, as the sun, Polaris,… … Universalium
Stellar classification — In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are… … Wikipedia
atmosphere — atmosphereless, adj. /at meuhs fear /, n., v., atmosphered, atmosphering. n. 1. the gaseous envelope surrounding the earth; the air. 2. this medium at a given place. 3. Astron. the gaseous envelope surrounding a heavenly body. 4. Chem. any… … Universalium
nebula — nebular, adj. /neb yeuh leuh/, n., pl. nebulae / lee , luy /, nebulas. 1. Astron. a. Also called diffuse nebula. a cloud of interstellar gas and dust. Cf. dark nebula, emission nebula, reflection nebula … Universalium
Brown dwarf — Brown dwarfs are sub stellar objects which are too low in mass to sustain hydrogen 1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no… … Wikipedia
Earth Sciences — ▪ 2009 Introduction Geology and Geochemistry The theme of the 33rd International Geological Congress, which was held in Norway in August 2008, was “Earth System Science: Foundation for Sustainable Development.” It was attended by nearly… … Universalium
galaxy — /gal euhk see/, n., pl. galaxies. 1. Astron. a. a large system of stars held together by mutual gravitation and isolated from similar systems by vast regions of space. b. (usually cap.) See Milky Way. 2. any large and brilliant or impressive… … Universalium