inclination, in astronomy, the angle of intersection between two planes, one of which is an orbital plane. The inclination of the plane of the moon's orbit is 5°9− with respect to the plane of the ecliptic (the plane of the earth's orbit around the sun). The inclination of the plane of the ecliptic relative to the plane of the earth's equator is 23°27−8.26”; this angle is called the obliquity of the ecliptic.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.