Question: how can you see stars when they are miles away?

Will Reynolds answered on 18 Jun 2012:

Hi ciara. Well stars get their energy from nuclear fusion and give out heat and light. Space is cold and has no air so its a vacuum. The heat from stars doesnt go very far (in space distances, the heat from our sun only goes to about mars before it becomes cold). But light keeps on going forever, so once light has been created it will travel in the direction it was emitted in until it hits something it cant pass through. As space is a vacuum there is nothing to stop the light so it keeps going until it gets to earth where we see it. However looking at stars is a bit like time travel because they are so far away that it takes a long time for the light to reach us. So the light we see today will have been created a long time ago and we will effectively be looking into the past. Our nearest star, after the sun is Alpha Centauri which is 4 light years away so when we look at that we are looking at things that happened 4 years ago!