Why does the Sun set on a flat Earth?
Sun and Moon · Updated
On a flat Earth the Sun never goes below the ground, so flat-Earth authors explain sunset in other ways. Samuel Rowbotham said it is perspective: a body vanishes at the horizon once it is less than one minute of arc above it. The Flat Earth Wiki lists perspective and Electromagnetic Acceleration, light that bends upwards.
Rowbotham’s law of perspective
In Zetetic Astronomy, Rowbotham argued that objects moving away over a flat surface seem to sink until they meet the horizon, and that the Sun does the same. FlatAtlas applies a measurable version of this rule: a body disappears once it is less than 1′ (one sixtieth of a degree) above the horizon. For a Sun 4,800 km up, that happens about 16.5 million km away. For Rowbotham’s 1,100 km, about 3.8 million km away. The flat Earth map itself is 40,000 km across.
How low could the Sun go? 10 cities
The lowest the Sun can be in the model is when it stands above the point of the map farthest from you, on the rim. This table gives that distance and the lowest angle above the horizon for both models.
| City | Farthest point of the map | Lowest Sun, Flat Earth Society (4,800 km) | Lowest Sun, Rowbotham (1,100 km) |
|---|---|---|---|
| Reykjavík | 22,850 km | 11.9° | 2.8° |
| London | 24,300 km | 11.2° | 2.6° |
| Bratislava | 24,650 km | 11.0° | 2.6° |
| New York | 25,500 km | 10.7° | 2.5° |
| Tokyo | 26,050 km | 10.4° | 2.4° |
| Los Angeles | 26,200 km | 10.4° | 2.4° |
| Singapore | 29,850 km | 9.1° | 2.1° |
| Sydney | 33,750 km | 8.1° | 1.9° |
| Cape Town | 33,750 km | 8.1° | 1.9° |
| Buenos Aires | 33,850 km | 8.1° | 1.9° |
In every city the lowest angle stays above 1′, so by this rule the Sun would always stay visible. FlatAtlas shows the same calculation for any place you pick.
Other flat-Earth explanations of sunset
The Flat Earth Wiki’s page on sunrise and sunset lists two mechanisms: the perspective effect described by Rowbotham, and Electromagnetic Acceleration, in which light curves upwards, so a distant Sun would appear lower and set. In this version the Sun is about 6,000 miles up. It publishes no formula for the curve, so FlatAtlas uses the straight-line model and says so.
What you can check at sunset
Watch the Sun’s size and the horizon. By straight-line geometry, a 32-mile Sun at the rim of the map would look about a fifth of its size overhead; the Flat Earth Wiki explains that it does not shrink by a magnification of the Sun at sunset, without figures. The real Sun looks about 0.5° wide from noon to sunset and sinks below the horizon from the bottom up. FlatAtlas shows where the model puts the Sun at any moment, next to where astronomy puts it.
Frequently asked questions
Does the Sun go below the horizon on a flat Earth?
In the flat Earth model the Sun stays above the map, so it can only appear to set. Rowbotham’s perspective rule and the Flat Earth Wiki’s Electromagnetic Acceleration (light bending upwards) are the explanations given.
How far away would the Sun have to be to set by perspective?
With a 1′ rule, a Sun 4,800 km up would have to be about 16.5 million km away, far beyond the 40,000 km flat Earth map.
How low can the Sun go from Bratislava in the flat Earth model?
About 11° above the horizon with the Flat Earth Society height, and about 2.6° with Rowbotham’s 700 miles.