Comet and Asteroid Orbital Element Distribution
Shown below is the distribution of asteroids
in semimajor axis,
contained in the inner solar system.
Note that the range of semimajor axis includes
Earth at 1 AU,
Mars at 1.52 AU,
and Jupiter at 5.2 AU.
Asteroids are shown in orange (small dots)
while comets are shown in cyan (larger dots).
The dotted line represents the Jupiter Tisserand invariant (T)
evaluated at T=3 and zero inclination (i).
This boundary very roughly separates small-bodies which are dynamically
bound to Jupiter from those which are not.
The region above this curve represents objects with T<3 (i.e. bound to Jupiter).
Notice that most comets as well as the
appear in that upper region (T<3, bound to Jupiter)
while nearly all asteroids are contained in the region below the curve
where T>3 (i.e. not bound to Jupiter).
This graph was created in June 2007
using all asteroids and comets
with "well-determined" orbits (specifically, numbered asteroids and comets).
A Postscript version of this plot is also available.