Chris Hadfield is a retired Canadian astronaut who was the first Canadian to walk in space. An engineer and former Royal Canadian Air Force Fighter pilot, Hadfield has flown two space shuttle missions and served as commander of the International Space Station.
I think in summary it comes down to this:
"Each time around you see the world slightly more for what it is - it's ONE place! This whole "thing" is just our collective, shared room - and we almost all miss that"
Cmdr. Chris Hadfield
'Overview' is a short film that explores this phenomenon through interviews with five astronauts who have experienced the Overview Effect. The film also features insights from commentators and thinkers on the wider implications and importance of this understanding for society, and our relationship to the environment. http://www.overviewthemovie.com/