radial motion

noun Astronomy.

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.

Compare redshift, tangential motion.

Also called radial velocity.

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British Dictionary definitions for radial velocity

radial velocity

noun

the component of the velocity of an object, esp a celestial body, directed along a line from the observer to the object

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