Relative angular momentum


In celestial mechanics, the relative angular momentum of an orbiting body relative to a central body is the moment of 's relative linear momentum:
where:
For a body in an unperturbed orbit about a central body, the orbital plane is stationary, and the relative angular momentum is perpendicular to the orbital plane.
For perturbed orbits where the orbital plane is in motion, the relative angular momentum vector is perpendicular to the orbital plane at only two points in the orbit.

Uses

In astrodynamics relative angular momentum is usually used to derive specific relative angular momentum :
where: