Latitude and longitude are the geographic coordinates used to define any location on Earth. Longitude and latitude are measured in degrees since the Earth is a sphere. These coordinates are most often used for navigation purposes when flying or on a ship where street signs are not available to define location.

The equator is a line of latitude. It is measured as zero degrees latitude and is located centrally between the North and South Poles. The prime meridian is measured as zero degrees longitude. The line passing north to south through Greenwich, England, is the prime meridian.

Lines of latitude are also called parallels. Parallels are equal distances apart from the equator to the poles. The equator is zero degrees latitude while the North and South Poles are 90 degrees latitude. Latitude is measured in degrees north or positive degrees, and degrees south or negative degrees. For example, the South Pole is 90 degrees S or -90 degrees.

Lines of longitude or meridians are perpendicular to lines of latitude. Lines of longitude begin at the prime meridian passing through England and are measured in positive degrees going east up to 180 degrees and negative degrees going west up to -180 degrees.

Each degree can be further broken down into 60 minutes or 60’. Each minute can be broken down into 60 seconds or 60”. This breakdown allows for more precise measurements of longitude and latitude.

Measurements of longitude are closely related to time. According to NASA, “Latitude and Longitude,” universal time is the time in Greenwich, England on the prime meridian. This is used to document astronomical events. Local time is the time zone relative to the position of the sun. The time zone is determined by the line of longitude. When the meridian is facing the sun, that time is defined as noon.