Answer:
Redshift, Blueshift, Doppler Effect, or Doppler Shift
Step-by-step explanation:
When a star is moving towards us, the light waves get compacted and the light appears blue, this is known as blueshift.
When a star is moving away from us, the light waves get spread apart and the light appears red, this is known as redshift.
Both of these are called the doppler effect or doppler shift.
I'm not sure which answer you need but I hope this helps!