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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...

radio astronomy

(Encyclopedia)radio astronomy, study of celestial bodies by means of the electromagnetic radio frequency waves they emit and absorb naturally. Radio waves also come from outside the Milky Way. These extragalact...

Kuiper, Gerard Peter

(Encyclopedia)Kuiper, Gerard Peter or Gerrit Pieter gĕrˈĭt pēˈtər kīˈpər [key], 1905–73, American astronomer, b. the Netherlands. Kuiper is considered to be the father of modern planetary science for his...

Saturnalia

(Encyclopedia)Saturnalia: see Saturn, in Roman religion. ...

gamma-ray astronomy

(Encyclopedia)gamma-ray astronomy, study of astronomical objects by analysis of the most energetic electromagnetic radiation they emit. Gamma rays are shorter in wavelength and hence more energetic than X rays (see...

X-ray astronomy

(Encyclopedia)X-ray astronomy, study of celestial objects by means of the X rays they emit, in the wavelength range from 0.01 to 10 nanometers. X-ray astronomy dates to 1949 with the discovery that the sun emits X ...

superior planet

(Encyclopedia)superior planet, planet whose orbit lies outside that of the earth. The superior planets are Mars, Jupiter, Saturn, Uranus, and Neptune. ...

Cassini's division

(Encyclopedia)Cassini's division: see Saturn.

Jovian planets

(Encyclopedia)Jovian planets, the planets Jupiter, Saturn, Uranus, and Neptune. They are all larger and more massive than the earth. Since they rotate faster, they are more flattened at the poles than are the terre...

Laplace, Pierre Simon, marquis de

(Encyclopedia)Laplace, Pierre Simon, marquis de pyĕr sēmôNˈ märkēˈ də läpläsˈ [key], 1749–1827, French astronomer and mathematician. At 18 he went to Paris, proved his gift for mathematical analysis to...