# Definition:Cardinal Points (Celestial)

## Definition The cardinal points of the celestial sphere are the north point, the sourth point, the east point and the west point:

### North Point of Horizon

The point on the celestial horizon through which the principal vertical circle passes is called the north point of the horizon.

### South Point of Horizon

The point on the celestial horizon exactly opposite the north point of the horizon is called the south point of the horizon.

### East Point of Horizon

Let an observer $O$ be facing the north point of the horizon $N$, facing directly away from the south point of the horizon $S$.

Let the celestial equator meet the celestial horizon at the points $E$ and $W$.

Let $E$ be the point on the right of $O$.

This is called the east point of the horizon.

### West Point of Horizon

Let an observer $O$ be facing the north point of the horizon $N$, facing directly away from the south point of the horizon $S$.

Let the celestial equator meet the celestial horizon at the points $E$ and $W$.

Let $W$ be the point on the left of $O$.

This is called the west point of the horizon.