Earth is roughly 8000 miles in diameter.
(a) I'm riding in a hot air balloon 1/2 mile above the surface of earth. Approximately how far away is the horizon? (In other words, how far away is the farthest point on the surface of Earth that I can see.)
(b) What if I'm in a plane 10 miles above the surface of the earth?
(c) What is I'm in a spaceship 200 miles above the surface of the earth?
