blue shift or blueshift, in astronomy, the systematic displacement of individual lines in the spectrum of a celestial object toward the blue, or shorter wavelength, end of the visible spectrum. The amount of displacement is a function of the object's relative velocity toward the observer. Most observed blue shifts are the result of the Doppler effect . The blue shift is the opposite of the red shift . Blue shifted celestial bodies are quite rare. Of the billions of known galaxies, only about 100, including the Andromeda galaxy, are blue shifted.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
See more Encyclopedia articles on: Astronomy: General