Excellent point. I think that one advantage of interstellar distance is we can effectively look back in time a great distance, so in effect we don't have a vis

Excellent point. I think that one advantage of interstellar distance is we can effectively look back in time a great distance, so in effect we don't have a visible radius, but a combination of time and distance. We can see thousands of light years back in time, thousands of light years away. However, we don't have that picture of Tau Ceti at 11 light years away. Perhaps thousands of years ago there was a civilization there that flourished and died - and we'll never know because their signs of life are outside our distance/time perception. A graph of Time/distance would be Time one axis, distance on the other and a diagonal line stretching up and to the right, showing what we could see at any given time. Thoughts? [edit: comment formatting ate my pretty ascii chart]