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albedo

(Encyclopedia)albedo ălbēˈdō [key], reflectivity of the surface of a planet, moon, asteroid, or other celestial body that does not shine by its own light. Albedo is measured as the fraction of incident light th...

Keeler, James Edward

(Encyclopedia)Keeler, James Edward, 1857–1900, American astronomer, b. La Salle, Ill. At the age of 21 he went on the Naval Observatory expedition to Colorado to observe the solar eclipse of July, 1878. In 1886 h...

Kirchhoff, Gustav Robert

(Encyclopedia)Kirchhoff, Gustav Robert go͝osˈtäf rōˈbĕrt kĭrkhˈhôf [key], 1824–87, German physicist. He served as professor of physics at the universities of Breslau (1850–54), Heidelberg (1854–74), ...

aurora borealis

(Encyclopedia)aurora borealis ôstrāˈlĭs [key], luminous display of various forms and colors seen in the night sky. The aurora borealis of the Northern Hemisphere is often called the northern lights, and the aur...

Slavic religion

(Encyclopedia)Slavic religion, pre-Christian religious practices among the Slavs of Eastern Europe. There is only fragmentary and scattered information about the myths and legends of the pagan Slavs, and it is not ...

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...

International Geophysical Year

(Encyclopedia)International Geophysical Year (IGY), 18-month period from July, 1957, through Dec., 1958, during a period of maximum sunspot activity, designated for cooperative study of the solar-terrestrial enviro...

planet

(Encyclopedia)planet [Gr.,=wanderer], a large nonluminous body of rock, gas, or ice that orbits the sun or another star, has a rounded shape due to gravity, and has cleared its orbit of smaller objects. The term, o...

Lacaille, Nicolas Louis de

(Encyclopedia)Lacaille, Nicolas Louis de nēkôläˈ lwē də läkäˈyə [key], 1713–62, French astronomer. As a result of his success in making meridional measurements in France under the patronage of the duke ...

terrestrial planet

(Encyclopedia)terrestrial planet, the earth or a planet that resembles the earth in its physical characteristics. The terrestrial planets in the solar system are the earth, Mercury, Venus, and Mars. These planets a...