Astronomy Answers: From the Astronomical Dictionary
The description of the word you requested from the astronomical dictionary is given
the great circle
plural great circles
A great circle is a special circle at the surface of a sphere (for
example of a planet or of the sky). You can recognize a great circle
by any of the following attributes:
- A great circle divides the surface of a sphere in two equal
- A great circle is the largest circle that fits on the sphere.
- If you keep going straight across a sphere then you go along a
- A great circle has the same center as the sphere that it lies
- The shortest route between two points, measured across the sphere,
is part of a great circle.
Some examples of great circles are: the ecliptic, the equator, any meridian.