I understand that since light needs time to travel, observing distant objects through a telescope means you are viewing them as they were in the past. That makes sense. So here's where I get confused...
Imagine if I had a spaceship capable of travelling at the speed of light and you and I carried out an experiment... You watched me blast off to a hypothetical planet orbiting Proxima Centauri today, 11 Aug 2011. For arguments sake, the planet is exactly 4 light years away. So, 4 years later on 11 Aug 2015 I arrive at the planet and at that same time, you look through an incredible telescope that is capable of seeing me wave back at you. But all you see is a bare planet with nobody there, right? I understand that this is because you are looking at the planet as it was when you watched me leave Earth, 4 years ago, even though I'm actually there on 11 Aug 2015. So my question is, to see me waving back at you on 11 Aug 2015, WHEN would you need to look through the telescope? 11 Aug 2019?
