Lunar distance method and the Nautical Almanac
Método de las distancias lunares y Almanaque Náutico
- Date
- 1763-1767 · confidence high
- Place
- Royal Observatory, Greenwich, London, United Kingdom
- Credited to
- Tobias Mayer and Nevil Maskelyne
- Field
- Movement
⚠️ Disputed: the sources disagree.
What it is
It finds Greenwich time by measuring with the sextant the angular distance between the Moon and the Sun or a star and comparing it with tables. Astronomer Royal Maskelyne published the Nautical Almanac from 1767 with distances pre-computed, with no need for a chronometer.
Regiomontanus (1474) and Werner (1514) had already proposed the idea; Mayer (1755) supplied accurate lunar tables, La Caille tried it at the Cape and Maskelyne made it operational. Priority is shared.
What it led to
- longitude determination on Cook's voyages and in the merchant marine
- annual nautical astronomical tables
- coexistence with the chronometer until the 19th century