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Roche limit

(Encyclopedia)Roche limit, the closest distance that a celestial body held together only by its own gravity can come to a planet without being pulled apart by the planet's tidal (gravitational) force. This distance...

Lamont, Johann von

(Encyclopedia)Lamont, Johann von yōˈhän fən läˈmônt [key], 1805–79, Scottish-German astronomer and magnetician, b. Scotland. In 1817 he went to Ratisbon to study at the seminary. He remained in Germany to ...

Perrine, Charles Dillon

(Encyclopedia)Perrine, Charles Dillon pərīnˈ [key], 1867–1951, American astronomer, b. Steubenville, Ohio. He was on the staff of Lick Observatory (1893–1909) and was (1909–36) director of the Argentine Na...

Al-Battani

(Encyclopedia)Al-Battani ălˌbətēˈnēəs [key], b. before 858, d. 929, Arab astronomer and mathematician. He is best known in astronomy for his improvements and corrections of the Ptolemaic tradition. His Kitab...

Bode's law

(Encyclopedia)Bode's law [for J. E. Bode], also known as Titius's law or the Titius-Bode law, empirical relationship between the mean distances of the planets from the sun. If each number in the series 0, 3, 6, 12,...

occultation

(Encyclopedia)occultation ŏkˌəltāˈshən [key], in astronomy, eclipse of one celestial body by another, e.g., when the moon lies between a star and the earth. Occultations of stars by the moon are important in ...

Flammarion, Camille

(Encyclopedia)Flammarion, Camille kämēˈyə flämäryôNˈ [key], 1842–1925, French astronomer and author. He served for some years at the Paris Observatory and the Bureau of Longitudes, and in 1883 he set up a...

astrophysics

(Encyclopedia)astrophysics, application of the theories and methods of physics to the study of stellar structure, stellar evolution, the origin of the solar system, and related problems of cosmology. The distinctio...

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...

eccentricity

(Encyclopedia)eccentricity, in astronomy: see orbit. ...