You are standing on a beach looking out into the ocean. Assuming your view is unobstructed, how far can you see?
(In reply to First Thoughts
Well, if you are looking at the sun, you can see 93 million miles, and
if you are looking past the sun, you can see even further. Let's
answer the more interest question of how far away is the horizon.
The Distance D to the horizon is one leg of a right triangle, whose
other leg is R (the radius of the earth) and whose hypoteneuse is R +
h, where h is the height of your eyes above sea level.
R^2 + D^2 = (R + h)^2
D^2 = h^2 + 2hR
For all practical purposes, D = sqrt(2hR).
Would anybody care to substitute in some reasonable values?