Definition:Colatitude/Terrestrial

Definition

Let $J$ be a point on Earth's surface that is not one of the two poles $N$ and $S$.

Let $\phi$ denote the latitude of $J$.

The (terrestrial) colatitude of $J$ is the (spherical) angle $90 \degrees - \phi$, that is:

if $J$ is in the northern hemisphere of Earth, the colatitude is the (spherical) angle $\sphericalangle NOJ$

if $J$ is in the southern hemisphere of Earth, the colatitude is the (spherical) angle $\sphericalangle SOJ$.

Also known as

Terrestrial colatitude is usually known in common parlance as just colatitude.

However, this term also encompasses other measurements of colatitude, for example celestial colatitude.

Hence on $\mathsf{Pr} \infty \mathsf{fWiki}$ the full term terrestrial colatitude is preferred, so as to forestall ambiguity, unless the context is clear.

Also see

• Definition:Colatitude
  • Definition:Celestial Colatitude

• Definition:Terrestrial Latitude
• Definition:Terrestrial Longitude

• Results about terrestrial colatitude can be found here.

Sources

• 1976: W.M. Smart: Textbook on Spherical Astronomy (6th ed.) ... (previous) ... (next): Chapter $\text I$. Spherical Trigonometry: $4$. Terrestrial latitude and longitude.