Celestial navigation glossary
Celestial horizon
The great circle 90° from your zenith; altitudes are measured up from it.
Where the course teaches it
Zenith, horizon and altitude, in the module The circle of equal altitude. Place a body's ground position, and turn one altitude into a circle of position in miles.
Taught alongside it
- Zenith
- The point on the celestial sphere straight above you; its declination is your latitude. The opposite point is the nadir.
- Circle of equal altitude
- Every place that sees a body at the same altitude: a circle centered on its GP.