Assuming that the earth is a perfect sphere, in units of the earth's radius, how high must one be to see exactly one half of the earth's surface?

Okay... okay... how about exactly one third of the earth's surface?

It seems like the answer to the first part is infinite at first.  However, light is affected by gravity, according to relativity, so I think there must be some height from which a whole hemisphere can be seen.

Posted by Tristan on 2004-09-29 18:55:00