Observing the altitude of Polaris primarily provides information about a location's which geographic coordinate?

• A. Latitude
• B. Longitude
• C. Altitude
• D. Declination

Answer: (A)

The altitude of Polaris is used to determine your latitude in the northern hemisphere. Polaris sits very close to the north celestial pole, so the angle it makes above the horizon equals the observer’s geographic latitude. For example, at 60° N Polaris would be about 60° up from the horizon; at the equator Polaris would be on the horizon; and at the North Pole it would be directly overhead at 90°. This is why observing Polaris mainly informs where you are north–south on Earth. It doesn’t give you longitude, which depends on time and Earth's rotation, and it isn’t a measure of your height above sea level. Declination is a celestial coordinate of the star itself, not a property that reveals your location.