blue shift

noun Astronomy.

1. a shift toward shorter wavelengths of the spectral lines of a celestial object, caused by the motion of the object toward the observer.

noun

1. a shift in the spectral lines of a stellar spectrum towards the blue end of the visible region relative to the wavelengths of these lines in the terrestrial spectrum: a result of the Doppler effect caused by stars approaching the solar systemCompare redshift

1. See under Doppler effect.