Answer:if the wavelength increases, it is that of a star moving away from us. If the wavelength decreases, it is that of a star moving away from us.
Explanation: Doppler effect is caused by a motion towards or away from the observer(this motion is called a radial velocity). The greater the Doppler effect, the greater the motion towards or away from us. Sideways motion does nor cause Doppler effect.
The formula for calculation of Doppler effect= (wavelength emitted by the source) - (wavelength observed by the observer) / wavelength emitted by the source
Which also equals to; V/c
Where v= speed and c= speed of light.
The amount the pattern is shifted can enable us to determine the speed of the objects in our line of sight.