Doppler Shift

Result of the relative motion of the light emitting object and the observer. If the source of light is moving away, the wavelength of the light is stretched (shifted towards lower frequencies). If the source of light is approaching, the wavelength of the light is compressed (shifted towards higher frequencies). These effects, called redshift and blueshift, respectively, are together known as Doppler shifts. The shift in the wavelength, λobserved – λrest, is given by a simple formula (v = velocity, c = speed of light):


Some or all content above used with permission from J. H. Wittke.