Timeline for What is the simplest way to prove the Earth is round?
Current License: CC BY-SA 3.0
9 events
| when toggle format | what | by | license | comment | |
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| Oct 11, 2023 at 17:07 | comment | added | NinjaDarth | With 4 points, you can prove a 2D surface is not flat - using the Flat Tetrahedron test. Their 6 distances give you a tetrahedron of volume 0. There's an even simpler test: they should also satisfy the 3D version of the triangle inequality. The distances for New York, Chicago, Houston and Miami don't! With 5 points and 10 distances, you can estimate the surface's curvature; e.g. add Los Angeles and you get 7902 miles diameter. But 6 points and 15 distances (e.g. add Seattle) can determine whether the curvature's really constant. For the Earth: it's not! The Earth's not a sphere. | |
| Oct 17, 2018 at 21:20 | comment | added | dgnuff | #1 can't prove it with two points, but it can with three. Place an observer at the equator at noon on the equinox (sun directly overhead), and two other observers 1,000 and 2,000 miles north respectively. Have all three measure the angle to the sun at the same time. If the earth is a sphere, there is provably no solution that can be found for the measured angles that allows a flat earth and a relatively nearby sun. | |
| Jul 6, 2018 at 20:30 | review | Suggested edits | |||
| Jul 7, 2018 at 2:20 | |||||
| Oct 23, 2017 at 6:54 | comment | added | Ruslan | @Java_User that'll only mean you're looking down. What if you try to look along your local horizontal, e.g. using a bubble level? You'll see that the horizon is a bit lower. And the higher you get, the lower the horizon appears to be. | |
| Jul 6, 2017 at 13:40 | comment | added | Java_User | #2 is not true. The horizon always comes up to your eye level. So the distance you can see cannot be attributed to the higher you are up. | |
| Aug 5, 2016 at 22:35 | comment | added | Nick T | #1 assumes that the sun is arbitrarily far away, and #2 can give conflicting results at long distances due to atmospheric refraction | |
| S Jul 19, 2015 at 22:06 | history | suggested | Robert Koritnik | CC BY-SA 3.0 | made headings instead of bullets |
| Jul 19, 2015 at 21:18 | review | Suggested edits | |||
| S Jul 19, 2015 at 22:06 | |||||
| Jun 24, 2011 at 11:05 | history | answered | Grant Thomas | CC BY-SA 3.0 |