What aspect of a celestial body does declination specifically measure?

Declination measures the angle of a celestial body from the celestial equator. It is analogous to latitude on Earth, indicating how far north or south an object is located in the sky. The celestial equator is an imaginary projection of the Earth's equator into space, and declination is expressed in degrees. Positive values indicate positions north of the celestial equator, while negative values indicate positions to the south.

Understanding declination is crucial for navigation as it helps in pinpointing the location of stars and other celestial bodies in the night sky, facilitating the use of these bodies for navigation and the establishment of celestial coordinates. This concept is fundamental in celestial navigation, as mariners often rely on the positions of stars, which are described using their declination along with right ascension.