2. You are here! But how do I know where here is?

3. Longitude and Latitude

4. Location on the Earth The earth is effectively a sphere, so how do we describe where a point is on its surface? The most common way to locate points on the surface of the Earth is by standard, geographic coordinates called latitude and longitude.

5. Location on the Earth These coordinates values are measured in degrees, and represent angular distances calculated from the center of the Earth.

6. Lines of Latitude Lines of Latitude are the horizontal lines shown running east-to-west on maps.

7. The Equator An imaginary line on the Earth's surface positioned equal distance from the North Pole and South Pole is called the Equator.

8. The Equator It divides the Earth into a Northern Hemisphere and a Southern Hemisphere.

10. Longitude Lines of longitude, also called meridians, run perpendicular to lines of latitude, and all pass through both poles.

11. Longitude

12. Prime Meridian The meridian of longitude, at 0 degrees, is called the Prime Meridian. It is used as the origin for the measurement of longitude.

13. Prime Meridian The meridian of Greenwich, England, is the internationally accepted prime meridian in most cases.