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Tombaugh, Clyde William

(Encyclopedia)Tombaugh, Clyde William tŏmˈbô [key], 1906–97, American astronomer, b. Streator, Ill. Although lacking formal training or a college degree, he was hired in 1929 as an assistant by the Lowell Obse...

Ceres, in astronomy

(Encyclopedia)Ceres sîrˈēz [key], in astronomy, a dwarf planet, the first asteroid to be discovered. It was found on Jan. 1, 1801, by G. Piazzi. He took three distinct observations; on the basis of these the mat...

Le Verrier, Urbain Jean Joseph

(Encyclopedia)Le Verrier, Urbain Jean Joseph ürbăNˈ zhäN zhôzĕfˈ ləvĕryāˈ [key], 1811–77, French astronomer who made calculations that led to the discovery of the planet Neptune. In considering the per...

Trojan asteroids

(Encyclopedia)Trojan asteroids, asteroids that revolve about the sun in the same orbit as a planet, occupying stable positions (known as Lagrangian points) either about 60° ahead of the planet in the orbit or abou...

Alpha Centauri

(Encyclopedia)Alpha Centauri ălˈfə sĕntôrˈē [key], brightest star in the constellation Centaurus and 3d-brightest star in the sky; also known as Rigil Kent or Rigil Kentaurus; 1992 position R.A. 14h39.1m, De...

Mercury, in astronomy

(Encyclopedia)Mercury, in astronomy, nearest planet to the sun, at a mean distance of 36 million mi (58 million km); its period of revolution is 88 days. Mercury passes through phases similar to those of the moon a...

Pegasus, in astronomy

(Encyclopedia)Pegasus pĕgˈəsəs [key], in astronomy, northern constellation lying SW of Andromeda and SE of Cygnus. It is named for the mythological winged horse Pegasus. The constellation is easily recognized b...

opposition

(Encyclopedia)opposition, in astronomy, alignment of two celestial bodies on opposite sides of the sky as viewed from earth. Opposition of the moon or planets is often determined in reference to the sun. Only the s...

Adams, John Couch

(Encyclopedia)Adams, John Couch, 1819–92, English astronomer, grad. St. John's College, Cambridge, 1843. By mathematical calculation based on irregularities in the motion of Uranus, he predicted the position of t...

ring, in astronomy

(Encyclopedia)ring, in astronomy, relatively thin band of rocks and dust and ice particles that orbit around a planet in the planet's equatorial plane. All four of the giant planets in the solar system—Jupiter, S...