Cartographers and geographers use horizontal and vertical lines called latitudes and longitudes to locate points on the globe. These lines form Earth's geographical coordinates and represent the angular distance of any location from the center of the Earth. Both latitudes and longitudes are measured in degrees (°) and minutes (′).
Dividing Earth Into Hemispheres
The Earth, almost a sphere, rotates around its axis, a shape scientists call a spheroid or ellipsoid. A line passing through the Earth's center along its rotational axis intersects the North and South Poles. The equator, an imaginary line perpendicular to this axis, is equidistant from the Poles and divides the globe into the Northern and Southern Hemispheres. Locations on the equator experience consistently high temperatures and at least 12 hours of daylight every day. During the equinoxes in September and March, the Sun is directly overhead the equator, resulting in almost exactly 12-hour days and nights.
Imaginary Circles: Latitudes and Longitudes
Latitudes, often called parallels or circles of latitude, are imaginary circles parallel to the equator. They run laterally (left to right) on a map where north is up. Latitudes specify the north-south position of a location. Locations in the Northern Hemisphere have northern latitudes (suffix N), while those in the Southern Hemisphere have southern latitudes (suffix S).
Notable Latitudes
East-West Locations: Longitudes
Longitudes run from the geographical North Pole to the South Pole, intersecting the equator. They specify the east-west position of a location. The Prime Meridian at 0° longitude divides the Earth into the Eastern and Western Hemispheres. The Earth is divided into 360 longitudes, with the meridian opposite the Prime Meridian known as the antimeridian (180° longitude).
Timekeeping and Longitudes
Modern timekeeping systems use longitudes as references. Time zones are defined by the Prime Meridian and the longitudes.
Remembering Latitudes and Longitudes
A simple way to remember their orientation is that longitudes are long, and latitudes are lateral.
The Significance of Great Circles
Great Circles, formed by a plane passing through the Earth's center, are crucial for studying migration, shipping, and airline routes. The equator and the circles created by the meridians form Great Circles, and the shortest line between two points on Earth's surface is always the arc of a Great Circle.
This overview provides a fundamental understanding of latitudes and longitudes, essential for geography, navigation, and understanding Earth's hemispheres and time zones.
