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spectral class

(Encyclopedia)CE5 spectral class, in astronomy, a classification of the stars by their spectrum and luminosity. In 1885, E. C. Pickering began the first extensive attempt to classify the stars spectroscopically....

telescope

(Encyclopedia)CE5 Mirror arrangements for a reflecting telescope telescope, traditionally, a system of lenses, mirrors, or both, used to gather light from a distant object and form an image of it. Traditional o...

Ai Weiwei

(Encyclopedia)Ai Weiwei īˈ wāwā [key], 1957–, Chinese artist, architect, filmmaker, and political activist. He is the son of poet Ai Ch'ing, who was internally exiled (1958–76) to work camps with his family...

Silk Road

(Encyclopedia)Silk Road, ancient overland trade route linking Asia and Europe, consisting of a network of caravan routes running from China across central Asia to the shores of the Mediterranean. Its starting point...

retrograde motion

(Encyclopedia)retrograde motion, in astronomy, real or apparent movement of a planet, dwarf planet, moon, asteroid, or comet from east to west relative to the fixed stars. The most common direction of motion in the...

red shift

(Encyclopedia)red shift or redshift, in astronomy, the systematic displacement of individual lines in the spectrum of a celestial object toward the red, or longer wavelength, end of the visible spectrum. The effect...

space science

(Encyclopedia)space science, body of scientific knowledge as it relates to space exploration; it is sometimes also called astronautics. Space science draws on the conventional sciences of physics, chemistry, biolog...

Peirce, Charles Sanders

(Encyclopedia)Peirce, Charles Sanders pûrs [key], 1839–1914, American philosopher and polymath, b. Cambridge, Mass., grad. Harvard, 1859; son of Benjamin Peirce. Except for occasional lectures he renounced the r...

transit

(Encyclopedia)transit, in astronomy, passage of a body across a meridian or passage of a small body across the visible disk of a larger one. (The passage of a large body across a smaller one is called an eclipse or...

Thomas, Dylan

(Encyclopedia)Thomas, Dylan dĭlˈən [key], 1914–53, Welsh poet, b. Swansea. An extraordinarily individualistic writer, Thomas is ranked among the great 20th-century poets. He grew up in Swansea, the son of a te...