Revise GCSE Physics


Question:Why do we see stars as being older than they really are?

It takes time for the light from the star to reach us.

So if a star is 5000 light-years away, then the light arriving at our telescopes today, left the star 5000 years ago; so we are seeing what the star was like then, 5000 years ago, not what it is like today. In fact many of the stars that we can see in the sky will not even be there anymore because they will have died while the light from them is travelling towards us.