Empirical Earth · Flight & Navigation

Celestial navigation works — and only on a globe

The claim

“Sailors navigated for centuries without satellites — doesn’t that work fine on a flat Earth?”

What is measured

A sextant, an almanac and an accurate clock fix your position anywhere on Earth by solving spherical triangles. That geometry only works on a rotating globe. It has guided ships across every ocean for centuries, and unlike flat-Earth schemes it delivers longitude.

What would show this is wrong

a self-consistent flat-Earth navigation method that yields correct latitude and longitude worldwide without assuming a sphere, matching the accuracy celestial navigation achieves on every ocean.

Sources

  1. Celestial navigation. A sextant measures a body’s altitude; with the exact time and the Nautical Almanac, sight reduction (spherical trigonometry) yields a line of position, and two lines fi link
  2. Longitude by chronometer. Longitude needs accurate time at a reference meridian (Harrison’s chronometer); Earth turns 15° of longitude per hour, so comparing local with Greenwich time gives link
  3. The nautical mile. Defined as one minute of arc of latitude (1,852 m); Earth’s polar circumference is therefore very nearly 21,600 NM (360° × 60′). Britannica link
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