celestial sphere Imaginary sphere of infinite radius used to define the positions of celestial bodies as seen from Earth, the centre of the sphere. The sphere rotates, once in 24 hours, about a line that is an extension of the Earth's axis. The position of a celestial body is the point at which a radial line through it meets the surface of the sphere. The position is defined in terms of coordinates, such as declination and right ascension or altitude and azimuth, which refer to great circles on the sphere, such as the celestial equator or the ecliptic.
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Equator , equator •cater, crater, creator, curator, data, debater, delator, dumbwaiter, equator, freighter, frustrater, gaiter, grater, gyrator, hater, later,… azimuth , az·i·muth / ˈazəmə[unvoicedth]/ • n. the direction of a celestial object from the observer, expressed as the angular distance from the north or south… perigee , perigee (astron.) point in the orbit of a planet that is nearest to the earth. XVI. In early use varying with forms directly repr. L. and Gr.; — F. p… Maps , Maps have been made for thousands of years as a means to convey information about the surface of the Earth. Some maps are highly complex, organized d… Dip Pole , dip pole A point, usually on the Earth's surface, where the magnetic vector is vertical, i.e. the inclination is 90°. A positive (downward) inclinati… Slope , Skip to main content Slope slope / slōp/ • n. 1. a surface of which one end or side is at a higher level than another; a rising or falling surface: h…
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