Longitude (shown as a vertical line) is the angular distance, in degrees, minutes, and seconds, of a point east or west of the Prime (Greenwich) Meridian. Lines of longitude are often referred to as meridians.
Distance Between Lines
If you divide the circumference of the earth (approximately 25,000 miles) by 360 degrees, the distance on the earth’s surface for each one degree of latitude or longitude is just over 69 miles, or 111 km. Note: As you move north or south of the equator, the distance between the lines of longitude gets shorter until they actually meet at the poles. At 45 degrees N or S of the equator, one degree of longitude is about 49 miles.
Minutes And Seconds
For precision purposes, degrees of longitude and latitude have been divided into minutes (‘) and seconds (“). There are 60 minutes in each degree. Each minute is divided into 60 seconds. Seconds can be further divided into tenths, hundredths, or even thousandths. For example, the Natural History Museum, London, is located at 51 degrees, 29 minutes, and 46 seconds north of the equator, and 0 degrees, 10 minutes and 35 seconds west of the Prime Meridian.
Relative Location of a city or destination on the planet is its relationship to another place or nearby landmarks. For example, the US Capitol is located about 38 miles southwest of Baltimore, the capital city of Maryland.
Absolute Location is the definitive location of a place using a recognized coordinate system. In terms of latitude and longitude, the Natural History Museum, London 51° 29′ 46″ North, 0° 10′ 35″ West.