What does the term 'declination' refer to in navigation?

The term "declination" in navigation refers specifically to the angular distance of a celestial object from the celestial equator. This concept is essential for celestial navigation, as it helps navigators determine the position of celestial bodies such as stars and planets relative to the Earth.

In the celestial sphere, the celestial equator is an imaginary line that represents the Earth's equator projected into space. Declination is measured in degrees north or south of this equator. A celestial object with a declination of +30 degrees would be located 30 degrees north of the celestial equator, while an object with a declination of -30 degrees would be 30 degrees south of the equator.

Understanding declination allows navigators to accurately calculate their positions at sea by referencing the positions of stars and using tools like sextants to determine altitude angles, making it a fundamental aspect of celestial navigation.