In reference to the OP, what "keeps light in" on a spherical Earth?
not a whole lot
most gets reflected back in to space and even then only some of the IR stays in see green house effect
Yes, which is why I wanted to know why the first poster thought that light needed to be "kept in" on any kind of Earth.
it was poorly phrased. what I meant was what keeps light from falling, as the earth goes up.
and @jack.
Lolno,
you can't just declare Equivalency Principal!!!!
if an air molecule was going at some speed v out towards space, then it would still be contained within earth's atmosphere, as gravity would cause it to come back. however, when it flies at the top of the ice wall with relative speed v, it can go over, with nothing to keep it in. and don't you think such an Ice wall would be observable if we went to the tip of Chile, and looked with a telescope or something?