Our messenger for most of our astronomical knowledge is light, and in its broadest sense, this encompasses the entire array of energies known as the electromagnetic spectrum. That s per second. It sounds really fast, but the universe is so huge that even this prodigious velocity is best described as a snail s pace when we talk about seeing the most distant objects. It may take 8-15 billion years for the most distant information to reach our telescopes. That s 8-15 billion light years away.
Delays are shorter in our solar system.
That sunset you witnessed last evening showed old Sol the way it was about eight minutes before it set. The light radiating from the North Star shows the way it appeared around 1570. By the time we reach out and observe the Andromeda Galaxy, we are now about two million years into the past. Millions of people claim to have seen them, but the evidence is slim that we are being visited by extraterrestrials. Still, there exists certain observed phenomena which lack good scientific explanations.