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sunspots

(Encyclopedia)sunspots, dark, usually irregularly shaped spots on the sun's surface that are actually solar magnetic storms. The spots are darker because the temperature of the spots is lower than that of the surro...

radar astronomy

(Encyclopedia)radar astronomy, application of radar to the determination of distances and planetary features within the solar system, such as rotation rates. A short burst of radio waves is transmitted in the direc...

synodic period

(Encyclopedia)synodic period sĭnŏdˈĭk [key], in astronomy, length of time during which a body in the solar system makes one orbit of the sun relative to the earth, i.e., returns to the same elongation. Because ...

astronomical unit

(Encyclopedia)astronomical unit (AU), mean distance between the earth and sun; one AU is c.92,960,000 mi (149,604,970 km). The astronomical unit is the principal unit of measurement within the solar system, e.g., M...

Hawthorne

(Encyclopedia)Hawthorne. 1 City (2020 pop. 88,083), Los Angeles co., S Calif., a suburb of Los Angeles; inc. 1922. Located in an oil- and gas-producing area, ...

Ganymede, in astronomy

(Encyclopedia)Ganymede gănˈēmēdˌ [key], in astronomy, one of the moons, or natural satellites, of Jupiter; the largest natural satellite in the solar system, it is larger than the planet Mercury. ...

Tychyna, Pavlo

(Encyclopedia)Tychyna, Pavlo, 1891–1967, Ukrainian poet. Tychyna's first volume of verse (Solar Clarinets, 1919) revealed a strong symbolist influence. His later poetry, including The Party is our Guide (1934) an...

Orbiting Geophysical Observatory

(Encyclopedia)Orbiting Geophysical Observatory (OGO), series of six orbiting observatories (see observatory, orbiting) launched between 1964 and 1969 by the National Aeronautics and Space Administration (NASA) to s...

Stonehenge

(Encyclopedia)Stonehenge stōnˈhĕnjˌ [key], group of standing stones on Salisbury Plain, Wiltshire, S England. Preeminent among megalithic monuments in the British Isles, it is similar to an older and larger mon...

perturbation

(Encyclopedia)perturbation pŭrˌtərbāˈshən [key], in astronomy and physics, small force or other influence that modifies the otherwise simple motion of some object. The term is also used for the effect produce...