# Orbiting body

(Redirected from Secondary 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 (${\displaystyle m_{2}}$),[1] which is less massive than the primary body (${\displaystyle m_{1}}$).

Thus, ${\displaystyle m_{2} or ${\displaystyle m_{1}>m_{2}}$.

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 astronomical object, such as a planet, dwarf planet, moon, moonlet, asteroid, or comet.