This is a video of a plane at 70000 ft altitude, or 13 miles high - it is twice the distance of a commercial plane and you can see the horizon very clearly from up there - 13 miles on the ground does not seem far, but viewing from the air is altogether breath taking - truly awesome and amazing -

http://www.youtube.com/watch_popup?v=1PmYItnlY5M

What a wonderful world!