nuimshaan wrote:If I had a really good pair of binoculars and could actually see what was happening on the surface of another planet...would I be seeing what was going on right then...like while I was standing there using those binoculars, was I seeing things on the surface of the planet as they were right then...or was I seeing into the past?
Let's say for example we radio one of our moon bases, and tell them to suit up at noon tomorrow..Earth time..use a good set of binoculars..and see if they can see me outside tomorrow at noon using my binoculars to see if they are obeying orders...would we see each other at the same time?
What happens if the moon was light years away...simply located over there instead of here...what would happen tomorrow at noon....let's say the astronauts didn't even know we moved them way over there...they just followed orders and were outside with their binoculars at noon tomorrow...and so are we tomorrow at noon with ours...let's assume our binoculars are good enough to at least see the moon, even though it's way over there...
Well you are talking about carrying "information", which is presumed to travel at the speed of light "c", at most. Any information which exceeds c while traveling would violate the Causality Principle, e.g. after you see a flashlight, you could send a massage to the person who holds it "never open the flashlight" BEFORE he opens it. And if he does not open it, how would you see it and send the message?! It is a paradox, which is caused by some information which had traveled with a speed more than the speed of light.
So returning to your example, your radio signal would propagate at c in space and reach the moon after X years, if it is X light years away. Thus, the astronauts would suit up after X years and 1 day after you send the signal. You have to wait that much time in earth-time as well.
edit: Well I have just noticed, there is some problem with my flashlight example, you would not send a message before the event if the light have reached you already. However, I hope you've got the message. (If you don't I'll manipulate my example)