I posted this in mad scientist this morning, but the board has had no hits all day, so i'm gonna try my luck here...


As I'm sure we all know, the light we see from a lot of the stars is old...now let's say in theory I could go to a star 50 million light years away...and view light reflecting off of the earth...would I, with the best telescopes available today, be able to see in any detail happenings on earth? If not with todays telescopes, does the reflected light have enough detail to show this?

or more simply, does reflected light lose any quality as distance from the source increases?

If you had a perfectly coherent light source (like an incredibly powerful laser) aimed out into space, then the power/detail you'd receive with a decent telescope would be ok.. but consider, with the BEST telescopes available today, you'd be hard pressed to see detail even one light year away.

Go look at information on stellar objects around the 50lgt year mark, see how bright they have to be for you to see them, and then realise how ridiculous your question is.

I'm not sure if you answered the question on the bottom, but whatever...

reflected light, like light from a source, does loose quality over a distance unless in a complete vacume where nothing is present but the light. the reason being that as light travels it hits bits or things floating in space. while space is a vacume, it is not a complete vacume and there is ALOT of crap floating around out there. could somebody whip out some equations cuz i cant remember any and i am too lazy to look for them myself.

no, it�s not ridiculous. But you may have heard in school about how a binocular works. So it�s not the quality, it�s the size that matters. To see any details on the earth, you would probably need something at the size of a whole galaxy.

the light would not lose quality, assuming that you mean quality as in clarity. its not like it would become any more blurry. it WOULD, however become much dimmer, and not to mention tiny.