The polar distance of any point is its distance in arc from either pole.
On g g is a movable pivot, to which h, which determines the pole, k0 h being the polar distance.
The angle through the celestial pole, between these two positions, is double the polar distance.
The polar distance, or angular distance from the nearest pole, is the complement of the latitude.
This is due to the increase in declination, or decrease in the star's polar distance.
The latitude is found by further increasing or diminishing this altitude by the polar distance of the star.
Since ZOQ is a right angle, it follows that the sum of the polar distance and the latitudinal co-ordinates is always 90.
Instead of it is frequently used the complementary angle ZOP, known as the polar distance of the body.