proper motion

proper motion, in astronomy, apparent movement of a star on the celestial sphere, usually measured as seconds of arc per year; it is due both to the actual relative motions of the sun and the star through space. Proper motion reflects only transverse motion, i.e., the component of motion across the line of sight to the star; it does not include the component of motion toward or away from the sun. The most distant stars show the least proper motion. Barnard's Star, one of the closest stars, has the largest measured proper motion, 10.27 sec of arc per year. The average proper motion of the stars that can be seen with the naked eye is 0.1” per year.

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

More on proper motion from Fact Monster:

  • Barnard's star - Barnard's star Barnard's star, star with the largest observed proper motion (rate of motion ...
  • Sherburne Wesley Burnham - Burnham, Sherburne Wesley Burnham, Sherburne Wesley, 1838–1921, American astronomer, b. ...
  • Arcturus - Arcturus Arcturus , brightest star in the constellation Boötes and 4th-brightest star in the ...
  • Friedrich Wilhelm Bessel - Bessel, Friedrich Wilhelm Bessel, Friedrich Wilhelm , 1784–1846, German astronomer and ...
  • Royal Greenwich Observatory - Royal Greenwich Observatory Royal Greenwich Observatory, astronomical observatory established in ...

See more Encyclopedia articles on: Astronomy: General