To plot a ship's position on a map using the sun or stars, sailors traditionally used a sextant to measure the angle between the celestial body and the horizon.

Here's how it worked:

1. Sextant: The sextant is a handheld instrument with a mirror that reflects the image of the sun or star onto a graduated arc.

2. Angle Measurement: The sailor carefully aligns the sextant to make the celestial body appear to touch the horizon. The angle between the horizon and the celestial body is then read off the graduated arc.

3. Time Measurement: Simultaneously, the sailor notes the exact time (using a chronometer) when the observation was made.

4. Celestial Navigation Tables: Using these measurements, along with pre-calculated tables (Nautical Almanac), the sailor could determine the ship's latitude and longitude.

Other tools:

* Compass: Used to determine the ship's heading.

* Chronometer: A highly accurate clock used to keep track of time, essential for celestial navigation.

* Nautical Almanac: A book of astronomical data used to calculate the position of celestial bodies.

These tools, combined with a keen understanding of celestial mechanics, allowed sailors to navigate the oceans for centuries before the advent of modern navigation systems.