This story was originally published on Smarter Than That in 2008. We are republishing a lightly edited version on Popular Science in light of recent interest in the subject. Humanity has known Earth is round for a few millenia, and I’ve been meaning to show more methods that prove the world is not flat.
Humanity has known Earth is round for a few millenia. The history of our species’ intellectual pursuit is important and interesting. On we go, to the top 10 ways to know the Earth is unequivocally, absolutely, positively, 100% not flat!
Below are few ways in which you can check this. Full article with illustrations here.
1. Aristotle (who made quite a lot of observations about the spherical nature of the Earth) noticed that during lunar eclipses (when the Earth’s orbit places it directly between the Sun and the Moon, creating a shadow in the process), the shadow on the Moon’s surface is round. This shadow is the planet’s, and it’s a great clue about the spherical shape of the Earth.
2. If you’ve been next to a port lately, you might have noticed a very interesting phenomenon: Approaching ships do not just “appear” out of the horizon (like they should have if the world was flat), but rather seem to emerge from beneath the sea.
3. Aristotle (384-322 BCE), declared the Earth was round judging from the different constellations one sees while moving away from the equator.
4. The higher up you climb, the farther you will see. Usually, we tend to relate this to Earthly obstacles—like the fact we have houses or other trees obstructing our vision on the ground, and climbing upwards we have a clear view—but that’s not the true reason. Even if you stood on a completely clear plateau with no obstacles between you and the horizon, you would see much farther from the greater height than you would on the ground.
5. If you’ve ever taken a trip out of the country, specifically long-distance trips, you could notice two interesting facts about planes and the Earth:
- Planes can travel in a relatively straight line for a very long time and not fall off any edges. They can also circle the Earth without stopping.
- If you look out the window on a trans-Atlantic flight, you can, most of the times, see the curvature of the Earth on the horizon. The best view of the curvature is from the new plane by Virgin Galactic—the horizon looks curved, as it actually is from a distance.