What 'revolutions' have occurred in the field of geography?

There was an ancient society once, cant remember who but maybe egyptians, that actually was able to determine the circumfrence of the earth at a very early time by using geography and topography. They would stand on a hill that they knew how tall it was, then would see how far they could see to the horizon, then by measuring that distance relative to the height of the hill they were on they could determine the earths size within a few dozen kilometer- if I remember correctly. Im sorry I dont know much about it, I remember seeing it a couple weeks ago on a documentary but hopefully this will give you something to think about.

the planets which are recently discovered they are 100 light years away by NASA