The Andromeda paradox. Alice is sitting and watching the Andromeda galaxy through a telescope. Bob is running toward Alice and is also watching the galaxy through his teleccope. Apparently Bob (moving in regard to Alice) is seeing the galaxy at a point of time which is ahead of what Alice sees (who is "stationary").

I know it can be calculated just howuchnis differs, but is it possible to explain it so I can understand the principle? Why does moving alter the view (timewise) through the telescope and what happens if the stationary Alice viewer starts moving and catches up with Bob while still looking through her telescope?