Arcturus (ärktŏrˈəs) [key], brightest star in the constellation Boötes and 4th-brightest star in the entire sky; Bayer designation Alpha Boötis; 1992 position R.A. 14h15.3m, Dec. +19°13−. An orange giant of spectral class K2 III, it has an apparent magnitude of - 0.06; its diameter is about 10 times that of the sun and its luminosity about 100 times that of the sun. Arcturus is one of the nearest giant stars, at a distance of about 36 light-years, and has one of the largest proper motions (annual angular shift in position) of the bright stars. Its name is from the Greek meaning "guardian of the bear," and it can be found by following the extension of the curve of the handle of the Big Dipper (Large Bear).

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

More on Arcturus from Fact Monster:

  • Libra - Libra Libra [Lat.,=the scales], southern constellation lying on the ecliptic (the sun's ...
  • Boötes - Boötes Boötes [Gr.,=the herdsman], northern constellation located to the SE of the Big ...
  • Callisto, in Greek mythology - Callisto Callisto , in Greek mythology, an attendant of Artemis. Because she forsook her chastity ...
  • red giant - red giant red giant, starthat is relatively cool but very luminous because of its great size. All ...
  • Encyclopedia: Astronomy: Stars - Encyclopeadia articles concerning Astronomy: Stars.

See more Encyclopedia articles on: Astronomy: Stars

Play Hangman

Play Poptropica

Play Quizzes

Play Tic Tac Toe