When we look up into the night sky, we are also looking back in time. The light from the stars we see with our unaided eyes left those stars sometimes hundreds—if not thousands—of years ago. The arrival of Sirius in the winter skies always causes me to pause a moment and remember where I was and what I was doing nine years ago (the approximate time the light I'm now seeing left that star).
But if you look to the majority of bright, blue-white giants that form the Orion constellation, that light left well before you, me, our parents, grandparents, great grandparents, and in fact, this country were even born. I've marked up my photo from yesterday as a thought experiment.
As always, click for full size.
