What physical principle allows analysis of light to determine stellar speed?
Answer
Doppler effect
Determining the speed of distant stars relies fundamentally on applying the Doppler effect to the light reaching Earth. This effect, analogous to how the pitch of an ambulance siren changes based on its movement relative to an observer, causes a shift in the wavelength of light emitted by the star. This shift is the key measurement used by astronomers to calculate kinematic data for objects millions of kilometers per second away, treating the received light as a precise speedometer.
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