Calculating Latitude and Longitude

The system of latitude and longitude is the grid system used to uniquely locate any point on the surface of a sphere.  Lines of latitude are parallel to the equator, with the equator used as the reference with a latitude of 0°.  Latitude increases with angular distance from the equator, with the poles having latitudes of 90°N and 90°S respectively.  Latitude can be determined with reference to either the sun or the stars.

Lines of longitude are called meridians, with the Prime Meridian (0° longitude) arbitrarily selected as that passing through the Royal Observatory in Greenwich, England.  Longitude increases to the east and west as you move away from the Prime Meridian, with 180° longitude passing through the Pacific Ocean.  Lines of longitude are most widely spaced at the equator, and intersect at the poles.  Longitude is calculated by comparing the time at Greenwich with local solar noon by using an instrument called a chronometer.

Click here for a quiz about latitude, longitude, time, seasons and sun positions

Click here for practice problems for determining latitude and longitude

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