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Fraunhofer lines

(Encyclopedia)Fraunhofer lines frounˈhôfər [key]: see sun. ...

seasons

(Encyclopedia)CE5 The seasons are caused by the tilt of the earth's axis to the plane of its orbit about the sun. The Northern Hemisphere is tilted toward the sun in the summer and receives more direct rays than...

Young, Charles Augustus

(Encyclopedia)Young, Charles Augustus, 1834–1908, American astronomer, b. Hanover, N.H., grad. Dartmouth, 1853. He discovered the reversing layer of the solar atmosphere and proved the gaseous nature of the sun's...

luminosity

(Encyclopedia)luminosity, in astronomy, the rate at which energy of all types is radiated by an object in all directions. A star's luminosity depends on its size and its temperature, varying as the square of the ra...

solar time

(Encyclopedia)solar time, time defined by the position of the sun. The solar day is the time it takes for the sun to return to the same meridian in the sky. Local solar time is measured by a sundial. When the cente...

Ch'ing

(Encyclopedia)Ch'ing mănˌcho͞oˈ, mănˈcho͞oˌ [key], the last of the Imperial dynasties of China. Following foreign suppression of the Boxer Uprising, Tz'u Hsi changed course and allowed some moderate educa...

solstice

(Encyclopedia)solstice sŏlˈstĭs [key] [Lat.,=sun stands still], in astronomy, either of the two points on the ecliptic that lie midway between the equinoxes (separated from them by an angular distance of 90°). ...

perihelion

(Encyclopedia)perihelion pĕrˌəhēˈlēən [key], point nearest the sun in the orbit of a body about the sun. See apsis. ...

solar wind

(Encyclopedia)solar wind, stream of ionized hydrogen—protons and electrons—with an 8% component of helium ions and trace amounts of heavier ions that radiates outward from the sun at high speeds. The continuous...

aphelion

(Encyclopedia)aphelion əfēˈlēən, ăpˌhēˈ– [key], point farthest from the sun in the orbit of a body about the sun. See apsis. ...