Port of Tauranga

The Angle of the Sun

At noon (local time), the sun reaches its zenith or highest point in the sky.

As you move south of the equator, the sun is no longer directly overhead at noon, but forms an angle more and more north of the vertical position.

Your first step in calculating your latitude is to find what is called the Zenith Distance. This is a measure of the angle the noon sun makes with an imaginary vertical line.

Since the vertical line is at 90^o to the earths surface, the Zenith Distance is found by;

Zenith Distance = 90^o – Sextant reading

In the southern hemisphere the Zenith Distance is stated as an angle S (south). eg 12^oS

In the northern hemisphere, the Zenith Distance is stated as an angle N (north). eg 12^oN

Use the Sextant animation and the Latitude animation to find the Zenith Distance onboard your ship.

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