I wrote about Carl Sagan‘s Cosmos in a recent post on the One Book Meme. Tonight, twice during the documentary An Inconvenient Truth, Al Gore mentioned some Sagan quotes that I remembered from past reading. The first one was about the thickness – and hence the fragility – of the Earth’s atmosphere. He was saying that if you had a large model globe of the Earth and put a layer of varnish on it, the thickness of the varnish in comparison with the size of the globe would give a reasonably good idea of the thickness of the atmosphere in relation to the size of the real Earth. The second quote, which I shall never forget, pertains to a picture taken by Voyager I as it left the solar neighborhood for the depths of outer space.