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Celestial Mechanics

(study of forces and motion of celestial objects)

Celestial Mechanics is the application of Mechanics to celestial objects, e.g., planets, galaxies, Moons, etc. Mechanics, in turn is the branch of physics dealing with forces and motion. More specifically, Dynamics is the study of forces and resulting motions, e.g., orbits and Statics is the study of forces in the absence of motion, e.g., why the inside of the Moon doesn't collapse to allow it to grow smaller, and Kinematics is the study of motion without relation to the forces.

For example, Kepler's Laws , which describe orbits (Keplerian Orbit) fall under the heading of Kinematics, whereas Newton's Laws, which describe the way forces effect on orbits fall under Dynamics.