Dictionary
ra'dial mo'tion
Astron.
the component of the motion of a star away from or toward the earth along its line of sight, expressed in miles or kilometers per second and determined by the shift in the wavelength of light emitted by the star. Also called
ra'dial veloc'ity. Cf.
redshift, tangential motion. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.