Great circle

Definition

A great circle is the largest possible circle that can be drawn on a sphere, such as Earth, with its center coinciding with the center of the sphere. It represents the shortest path between any two points on the surface of the sphere.

5 Must Know Facts For Your Next Test

1. All meridians (lines of longitude) are great circles.
2. The Equator is a unique example of a great circle among lines of latitude.
3. Great circles are used in navigation to find the shortest distance between two points on Earth.
4. Airplane routes often follow great circles to minimize travel distance and time.
5. A great circle divides the sphere into two equal hemispheres.

Review Questions

• What distinguishes a great circle from other circles on a sphere?
• Why are great circles important in navigation?
• Name an example of a great circle that is not a meridian.

Related terms

Meridian: A line of longitude running from the North Pole to the South Pole.

Equator: The imaginary line around Earth's middle, equidistant from both poles, and representing zero degrees latitude.

Hemisphere: Half of a spherical object, typically divided by either an equatorial or longitudinal plane.