[kas-ter, kah-ster]
castor: see beaver.
Castor, bright star in the constellation Gemini; Bayer designation α Geminorum; 1992 position R.A. 7h34.1m, Dec. +31°54'. Slightly dimmer than Pollux, with which it forms the Twins, Castor has an apparent magnitude of 1.58, which still makes it one of the 25 brightest stars in the sky. Castor is actually a six-star system, being a visual triple each component of which is a binary star; the three components are an eclipsing binary and a pair of spectroscopic binaries. The two brightest components are white, main-sequence stars of spectral classes A1 and A5. The system is about 50 light-years distant.

Castor-oil plant (Ricinus communis).

Large plant (Ricinus communis) of the spurge family, probably native to Africa and naturalized throughout the tropics. It is grown commercially for the pharmaceutical and industrial uses of its oil and for use in landscape gardening because of its handsome, giant, fanlike leaves. The bristly, spined, bronze-to-red clusters of fruits are attractive but are often removed before they mature because of the poison concentrated in their mottled, beanlike seeds. There are hundreds of natural forms and many horticultural varieties of this species.

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or Castor and Pollux

(from Greek dioskouroi, “sons of Zeus”) Twin gods of ancient Greece and Rome. They aided shipwrecked sailors and accepted sacrifices for favourable winds. Castor was mortal and Pollux was immortal; when Castor was killed, Pollux disowned his immortality to join his brother. The pair were excellent horsemen and were said to have participated in the hunting of the Calydonian boar, the voyage of the Argo, and the rescue of their sister Helen (who had been captured by Theseus). They were believed to have aided the Romans in an important battle early in their history, and a temple in their honour was built in the Roman Forum.

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Castor may refer to:

Historical people

Fictional people

Science and Technology

  • Castor (star), α Geminorum
  • Castor (software), a data binding framework for Java
  • Castor bean, a poisonous spurge seed
  • Castor oil, the oil of the castor bean
  • Castor oil plant, the plant from which the castor bean grows
  • Castor wax, a type of wax produced from castor oil
  • Castor angle, alignment in the vertical longitudinal plane of a motor vehicle's wheels (misspelling of caster)
  • CASTOR at CERN is the acronym for CERN Advanced STORage manager, a data storage system used at CERN, Geneva, Switzerland. CERN is the European Laboratory for the Research in Particle Physics.
  • CASTOR, an acronym for "Centauro And Strange Object Research," a forward CMS calorimeter
  • CASTOR is the acronym for Cask for storage and transport of radioactive material (containers used to transport highly nuclear waste)
  • Castor, the genus name of (and in many Romance languages the word for) the beaver
  • the Castor (rocket stage)
  • a variant spelling of caster, a type of wheel
  • on the Saturnian moon Janus (moon)
  • a South Devon Railway 4-4-0ST steam locomotive of the South Devon Railway Eagle class



HMS Castor

Four ships of the Royal Navy have borne the name HMS Castor. Named after one of the Gemini twins in Greek mythology. Castor also means "he who excels".

  • HMS Castor was a 36-gun fifth-rate captured from the Dutch in 1781 by HMS Flora. One month later she was captured by the French Frippone off Cadiz.
  • HMS Castor was a 32-gun fifth-rate launched in 1785. She was briefly in French hands in 1794, but was recaptured. She was sold in 1819.
  • HMS Castor was a 26-gun fifth-rate launched in 1832. In 1860 she became a training ship. She was sold in 1902.
  • HMS Castor was a C-class light cruiser launched in 1915. She was sold in 1936.

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