Celestial navigation
From FlightSim
Celestial navigation is a means of fixing your position by measuring angles to objects in the sky, such as sun, moon and certain stars. It requires very accurate time (generally via a chronometer), specialized measuring equipment (sextant, etc.) and tables of the position of the various celestial objects at different times.
Celestial navigation, though originally developed for ships on the ocean, was used in the early days of aircraft crossing oceans and other long range navigation, at least through the mid 1950s.
Ernest K. Gann's excellent book Fate Is The Hunter has quite a bit on the subject, since Gann discusses flights over oceans and over much of the world from the late 1930s to the mid 1950s.
Here is an animation of using a sextant to measure the sun:
See also the Wikipedia entry Celestial navigation
