Apoapsis
Given two objects of which one orbits the other, for example a
planet and a
satellite,
apoapsis is the point in the satellite's orbit which is furthest (at the greatest distance) from the planet.
- If the object orbits the Earth, it's also known as apogee.
- If the object orbits the Sun, it's also known as aphelion.
- If the object orbits the Moon, it's also known as apolune.
The point of the closest approach is the
periapsis. According to
Kepler's laws of planetary motion; as a planet travels in an
elliptical orbit, around a
star; as the planet approaches the apoapsis, it will decrease in
velocity.\n