An orbit that can change in a largely unpredictable manner, or one where a tiny change in the position and/or the velocity of the orbiting body will produce major changes in the orbit. For example, when a small body such as a comet or asteroid makes a close encounter with a massive planet such as Jupiter, its post-encounter path will differ by millions of kilometres if the fly-by distance is altered by only a few hundred kilometres. The outcomes of such encounters are essentially unpredictable. The orbit of the object Chiron, which is perturbed by Saturn and Uranus, is also chaotic.
Subjects: Astronomy and Astrophysics.