What is any circle on the surface of a sphere whose center is at the center of the sphere?

Any circle on the surface of a sphere whose center is at the center of the sphere is known as a "great circle." Great circles represent the largest possible circles that can be drawn on a sphere and divide the sphere into two equal hemispheres. The equator of a planet and the lines of longitude are examples of great circles. In contrast, smaller circles that do not have the same center as the sphere are called "small circles."