30.7 : Coordinates and Map Projections

Coordinates and map projections are essential tools in accurately representing the Earth's surface for various applications, ranging from navigation to spatial analysis. The latitude and longitude coordinate system is a universally recognized framework for defining locations. Latitude specifies the distance of a point north or south of the equator, measured in degrees from 0° at the equator to 90° at the poles. Longitude indicates a location's position east or west of the prime meridian, spanning from 0° to 180°. Together, these measurements form a grid that can pinpoint any location on Earth, supporting systems such as GPS for global navigation.

Map projections address the challenge of representing the Earth's curved, three-dimensional surface on a flat plane. As this transformation inherently introduces distortions, different predictions are designed to prioritize certain geographic properties like shape, area, distance, or direction. For instance, the Mercator projection is renowned for preserving accurate directional relationships, making it invaluable for maritime navigation. However, it distorts the size of landmasses near the poles, causing regions like Greenland to appear much larger than they are relative to equatorial continents.

Different projections are tailored to specific needs. Conic projections, which involve projecting the Earth's surface onto a cone, are particularly effective for regional maps, as they minimize distortion over smaller areas. Azimuthal projections, centered on a single point, are commonly used in aviation because they preserve accurate direction and distances from the focal point. The Universal Transverse Mercator (UTM) system divides the Earth into 60 longitudinal zones, facilitating precise local mapping and engineering applications.

By combining precise coordinate systems with the most suitable map projections, cartographers can produce maps that reliably support diverse fields such as geography, construction, and navigation.