Re: who first discovered that when we look a the stars we look backin time

Hello, Kevin...

    This was known to be the case as soon as the speed of light was shown to be finite. That was 
accomplished by Roemer in 1676, who observed the timing of the eclipses of the satellites of Jupiter to do 
it.  See this Wikipedia article for more details:

        http://en.wikipedia.org/wiki/Rømer's_determination_of_the_speed_of_light