Chapter 3 · Try it yourself
Sun Angle Slider
The same beam of sunlight lands on every part of the Earth. Near the equator it hits straight on. Farther north or south it hits at a slant and spreads out, so each square meter gets less heat. Move the slider and watch the beam spread.
0° is the equator. Use the arrow keys or drag.
Jump to a place:
The equator
Heat per square meter, compared with the equator
100%
The same beam covers
1.0× as much ground
Warm enough for reef-building corals
Simplified: midday sunlight on the first day of spring or fall, when the sun is straight over the equator. Ocean currents can push reefs a little farther from the equator, or keep them away. That is the story of Place 03.