Sizu Riatto
Every Angle · Chapter 4

Where the Sun Rises

A camera that looks into a low sun sees nothing but glare. One line of trigonometry gives the bearing of sunrise and sunset on any day; check every camera's view against them.

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Opens on the book's house and plot. Change any number to your own and press Calculate.

A camera's view (the glare check)

Enter your latitude, then press Calculate.

The formula

  • Sunrise bearing A (from north, clockwise): cos A = sin(declination) ÷ cos(latitude); sunset = 360° − A
  • The declination is +23.44° at the June solstice, −23.44° at the December one, 0 at the equinoxes
  • The sun's height at noon = 90° − |latitude − declination|
  • A camera aimed at bearing b with a view w degrees wide sees from b − w/2 to b + w/2
  • A model: flat horizon, no refraction, the sun's center; hills and houses move the real times and bearings
The book's worked example, Chapter 4. At 40° N the winter sun rises at 121.3° and sets at 238.7°; in summer at 58.7° and 301.3°. At 51.5° N (London): winter 129.7° / 230.3°, summer 50.3° / 309.7°. The winter noon sun at 40° N stands 26.56° up, the summer one 73.44°. Camera 1 looks along 150°–250°, which holds the winter sunset: the glare lesson.
Check it. Stand where the camera will go at sunset in the season you are checking and point a phone compass at the sun: you should read within a few degrees of the calculator.

Honest limits. This is a model of the sun over a flat horizon: hills, trees and houses hide a low sun and shift its rising and setting. Never look at the sun directly; point the compass, not your eyes. The book's house was worked out on paper from published figures, not surveyed by us: measure your own, and walk your own plot at night. Prices are illustrative US prices from November 2026, shown without a currency sign; put in your own. Everything stays in your browser: no sign-up, nothing stored.

These calculators go with Every Angle (Make It Add Up, Book 2), where every number on this page is worked by hand.