Doppler spectroscopy

Doppler spectroscopy in astronomy utilizes the Doppler effect to study celestial objects. This effect describes the change in frequency of waves (like light) due to the relative motion between a source and an observer. When a star or galaxy moves towards us, its light is shifted to higher frequencies (blueshift); when it moves away, its light is shifted to lower frequencies (redshift).12

Astronomers measure these shifts in the light's spectrum to determine the object's velocity and direction. This technique is crucial for understanding the expansion of the universe, studying the orbits of binary stars, and detecting extrasolar planets by observing the wobble of their host stars.234