It may sound impossible, but it’s easy. You look into the past every night when you see the stars!
We measure the distance between stars in light- years. A light-year is the distance that light travels in one year, about six trillion miles!
When you look at a star that is ten light-years away, you’re really seeing light that left the star ten years ago, and has been traveling through space since then. That means that you’re actually looking at the star as it was ten years ago.
Astronomers have found stars that are eight billion light-years away. If you were to look at these distant stars, you would be looking far into the past, long before the earth existed.
In fact, some of the stars you look at tonight may not even exist anymore!