The transverse form of this phenomenon is purely relativistic, arising from time dilation.  In conjunction with the Hubble constant, it gives the distance to astronomical objects, while on Earth it is
The transverse form of this phenomenon is purely relativistic, arising from time dilation.  In conjunction with the Hubble constant, it gives the distance to astronomical objects, while on Earth it is used to determine the speed of planes and baseballs.  For ten points, name this change in frequency caused by the relative motion of two objects.
The transverse form of this phenomenon is purely relativistic, arising from time dilation.  
Doppler shift