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- Orbiting body

In astrodynamics, an **orbiting body** is any physical body that orbits a more massive one, called the primary body. The orbiting body is properly referred to as the **secondary body** (

*m*_{2}

*m*_{1}

Thus,

*m*_{2}*<**m*_{1}

*m*_{1}*>**m*_{2}

Under standard assumptions in astrodynamics, the barycenter of the two bodies is a focus of both orbits.

An orbiting body may be a spacecraft (i.e. an artificial satellite) or a natural satellite, such as a planet, dwarf planet, moon, moonlet, asteroid, or comet.

A system of two orbiting bodies is modeled by the Two-Body Problem and a system of three orbiting bodies is modeled by the Three-Body Problem. These problems can be generalized to an N-body problem. While there are a few analytical solutions to the n-body problem, it can be reduced to a 2-body system if the secondary body stays out of other bodies' Sphere of Influence and remains in the primary body's sphere of influence.^{[2]}

- Barycenter
- Double planet
- Primary (astronomy)
- Satellite
- Two-body problem
- Three-body problem
- N-body problem

- Web site: Dictionary of Technical Terms for Aerospace Use . . 2010-05-11.
- Book: Curtis, Howard D.. Orbital Mechanics for Engineering Students, 2e. Elsevier. New York. 2009. 978-0-12-374778-5.