I have a long commute in the morning (50 min) and I sometimes think during it. I was wondering how far can we see. Un-aided. If we have the standard 20/20 vision. I mean I can look to the East and see Mt Hood. I know it's an hour and a half away, probably 50 miles the way the crow flies. So can we see 50 miles? Could I see a person 50 miles away (across a flat surface)? But then we can see stars which are millions of miles away. Are we only seeing light and only because light travels? I mean were not seeing the physical star are we? Only it's light? Is it dependent on how big the object is? If so, how far can we see a giant object? If we can see "that" far, then how come we can't see the smaller object at say 20 miles if we can see 50? What is the limit? Is the reason we can see light from a long way off, because the light travels out from it? Anyone?