how come whenever you face a rainbow the sun is behind you?

Question: how come whenever you face a rainbow the sun is behind you?
- Keywords:
  light,
  rainbow,
  sun,
  weather
Asked by to Ian on 23 Jun 2014. This question was also asked by .
- Ian Stephenson answered on 23 Jun 2014:
  
  Because the light from the sun goes into the raindrop, and bounces off the back before getting reflected back to you.
  
  This diagram makes it pretty clear:

Question: how come whenever you face a rainbow the sun is behind you?