How does the lunar distance method work in celestial navigation?

The lunar distance method is a celestial navigation technique used to determine precise time when time is unknown by measuring the angular distance between the Moon and another celestial body. Navigators use this measured angle alongside a nautical almanac to calculate Greenwich time, which can then be used to solve a spherical triangle for positioning. First published in theory by Johannes Werner in 1524, the fuller method was utilized until around 1850 before being superseded by the marine chronometer.

What we know

• Lunar distance in celestial navigation is the angular distance between the Moon and another celestial body. [1, 2]
• The lunar distance method uses the measured angle and a nautical almanac to calculate Greenwich time or any other time. [2]
• The calculated time from the lunar distance method can be used in solving a spherical triangle. [2]
• The theory for the lunar distance method was first published by Johannes Werner in 1524. [2]
• The lunar distance method was used until about 1850, when it was superseded by the marine chronometer. [2]

Where to go next

• the bigger pictureWhat is celestial navigation?
• compared withHow does a marine chronometer replace the lunar distance method?
• whoWho was Johannes Werner?
• how it workedHow are the Galilean moons used in similar navigation methods?
• how we knowHow does celestial navigation use sights taken with the horizon?
• an unexpected connectionHow do Jupiter's moons relate to lunar distance navigation?A similar method to lunar distances uses the positions of the Galilean moons of Jupiter to calculate time and position.

Sources

• [1]Lunar distance (Wikidata Q1547342) · CC0 1.0
• [2]Lunar distance (navigation) · CC BY-SA 4.0
• [3]Celestial navigation · CC BY-SA 4.0
• [4]Lunar distance · CC BY-SA 4.0
• [5]Moon · CC BY-SA 4.0