The Lyapounov time (*L*) is a
parameter that measures the speed rate at which orbits diverge
(or, in other words, it measures how much chaotic an orbit is). *L*
is the period of time for the distance between two near possible
orbits to increase of a factor *e*. The bigger this value
is, the more stable is the orbit (*L* has typical values
of a few years for chaotic asteroids, upt to 5 million years for
the inner planets and hundred million years for the external
planets).

For a non chaotic orbit (above picture) the distance
between two near orbits that have similar initial
conditions, is a linear function of time. The two orbits
diverge slowly, and their distance can be expressed as a
linear function of time:
For chaotic orbits, the distance between two near orbits can be expressed as an exponential function of time with the formula: This formula means that after a period of
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