DOPPLER EFFECT (YR13)

This video shows the Doppler effect, and explains the ideas of red-shift and blue-shift.
BUT...
Don't forget, that as the entire electromagnetic spectrum produced by a star will be shifted, the star as seen from Earth will NOT change colour!
For red-shift, for example, the UV will be shifted into the visible, so you will still see the violet end of the visible spectrum.
It is the shifting of spectral lines (gaps in the spectrum) that enable us to measure red-shift or blue-shift.


Here's a neat animation of the shifting of spectral lines