An observer's latitude is the angular distance, in degrees, of her position above or below the equator. Someone on the equator lies at a latitude of zero degrees, someone in Las Cruces, New Mexico, has a latitude of 32.5 degrees, and someone at the North Pole has a latitude of 90 degrees.

Polaris is the North Star, located above the North Pole along the north celestial pole. When viewed from the equator it lies on the northern horizon (at an altitude of 0 degrees), and when viewed from the North Pole it lies directly overhead (at an altitude of 90 degrees). The closer the observer is to the North Pole, the higher Polaris appears in the sky.

The left-hand figure below shows an observer (red dot) on the surface of the Earth (blue globe). The rotational axis of the Earth and the equator are drawn with dashed lines, and the North Pole and the planetary direction of rotation are indicated. Polaris is the yellow star, located high above the North Pole. The observer begins at the equator, and advances toward the North Pole. Her latitude is the angle between her starting position on the equator and her current position. The altitude of Polaris is its angular height from the horizon (above the horizon). Both angles are shown.

The right-hand figure below shows the observer's view of Polaris in the sky, in sync with the changes in her position shown on the left. As the observer travels toward the North Pole, her latitude increases and the height of Polaris above the northern horizon increases as well. Why do the mountains and hills on the horizon disappear when she reaches a latitude of 80 degrees? At this high a latitude Polaris is so high in the sky (above her head) that she has to tilt her head way back, and can no longer see the ground while looking at the star above her.