The iconic “blue marble” photo taken by the crew of Apollo 17 in 1972. Image credit: NASA.

Five Impossible Facts That Would Have To Be True If The Earth Were Flat

It isn’t flat, and these simple observations that you can make from the ground can demonstrate it to anyone.

From any one location on the surface of the Earth, it’s impossible to tell what our planet’s shape is. Having a single vantage point, even with a clear horizon, allows you to see a handful of miles (or kilometers) in any direction, but that can only allow you to place constraints. The Earth could be flat, or spherical, or in hydrostatic equilibrium, or egg-shaped, or irregular, and you wouldn’t know. All that you can know, from a single location on our surface, is that the Earth is indistinguishable from flat beyond a certain degree. If the Earth is round, it must be quite large: more than a few hundred miles (or kilometers) in diameter.

A panorama of many images stitched together from V2 rockets from flights in 1948. The first images to see the curvature of the Earth were taken from the same rockets and the same missile base in 1946; this mosaic is even more illustrative. Image credit: Johns Hopkins University, Applied Physics Laboratory, U.S. Navy.

Of course, it actually is quite round: a near-perfect sphere, to better than 99% precision. If you leave Earth’s surface, it’s impossible not to see the true shape of the Earth, as it’s been unavoidable since we first traveled high enough to observe our planet’s curvature.