Inclination

The inclination of the orbit of any celestial body is the dihedral angle that the plane of that orbit makes with a stated reference plane.

By default, an astronomer measures or reports the inclination of any body with respect to the equator of that body's primary. But other reference planes are, on occasion, more appropriate.

For satellites of the Sun, the most common reference plane is the plane of the ecliptic, or the orbit of the earth around the sun.

For a satellite of any gas giant planet, with its system of multiple satellites, the usual reference plane is a Laplace plane, defined locally with regard to all of the satellites of the planet involved.

Inclinations
Inclination Inclinação