Definition
A method of determining an aircraft's position by measuring the angle between the horizon and a celestial body — such as the sun, moon, a planet, or a star — at a precise moment in time, then comparing those measurements against published tables to fix the aircraft's location on the Earth's surface.
Plain English
Working out where you are by measuring the angle of the sun, moon, or stars above the horizon, noting the exact time, and using those numbers to calculate your position.
Context Anchor
Seen in long-range, oceanic, polar, military, and backup navigation discussions.
Derivation
From the Latin caelestis, meaning 'of the sky or heavens.' Celestial navigation is literally navigation by reference to objects in the sky.
Why Pilots Care
It supplies an independent method for fixing position when GPS, radio aids, or other electronic systems are unavailable or unreliable.
Intuition Check
Celestial navigation does not mean simply flying by looking at the stars. It means using measured observations of sky objects, along with the exact time, to work out position.
Example Sentence 1
Before satellite-based systems, transoceanic crews relied on celestial navigation to confirm their position over open water.
Example Sentence 2
The flight instructor demonstrated celestial navigation by taking a noon sun sight and consulting the tables.