Historically, the apparent motions of the planets were described by European and Arabic philosophers using the idea of celestial spheres. This model posited the existence of perfect moving spheres or rings to which the … See more

Within a planetary system, planets, dwarf planets, asteroids and other minor planets, comets, and space debris orbit the system's See more

Newton's law of gravitation and laws of motion for two-body problems
In most situations, relativistic effects can be neglected, and See more

The above classical (Newtonian) analysis of orbital mechanics assumes that the more subtle effects of general relativity, such as See more

There are a few common ways of understanding orbits:
• A force, such as gravity, pulls an object into a curved path as it attempts to fly off in a straight line. See more

The following derivation applies to such an elliptical orbit. We start only with the Newtonian law of gravitation stating that the gravitational … See more

The analysis so far has been two dimensional; it turns out that an unperturbed orbit is two-dimensional in a plane fixed in space, and thus the extension to three … See more