The component of a star's velocity along the line of sight from Earth, measured through the Doppler shift of spectral lines. Positive radial velocity indicates the star is moving away from us, while negative values mean it's approaching.
From Latin 'radius' meaning ray or spoke, and 'velocitas' meaning swiftness. The term developed in the late 19th century as spectroscopy allowed astronomers to measure stellar motions toward or away from Earth using the Doppler effect.
Radial velocity lets us hear the cosmic symphony of stellar motion! By listening to how starlight's 'pitch' changes due to the Doppler effect, we can detect not only stellar motion but also the gravitational dance of unseen planets orbiting distant stars.
Complete word intelligence in one call. Free tier — 50 lookups/day.