  Using numerical simulations, we examine the structure of a cometary
population near a massive planet, such as a giant planet of the Solar system,
starting with one-planet approximation (the Sun plus one planet). By studying
the distributions of comets in semimajor axis, eccentricity, pericenter, and
apocenter distances, we have revealed several interesting features in these
distributions. The most remarkable ones include (i) spatial accumulation of
comets near the planetary orbit (which we call the `cometary belt') and (ii)
avoidance of resonant orbits by comets. Then we abandon one-planet
approximation and examine as to how a cometary belt is modified when the
influence of all four giant planets is taken into consideration. To this end,
we simulate a stationary distribution of comets, which results from the
gravitational scattering of the Kuiper belt objects on the four giant planets
and accounts for the effects of mean motion resonances. Accounting for the
influence of four giant planets makes the cometary belts overlapping, but
nevertheless keeping almost all their basic features found in one-planet
approximation. In particular, the belts maintain the gaps in the (a,e)- and
(a,i)-space similar to the Kirkwood gaps in the main asteroid belt. We conclude
that the large-scale structure of the Solar system is featured by the four
cometary belts expected to contain 20-30 millions of scattered comets, and only
a tiny fraction of them is currently visible as Jupiter-, Saturn-, etc. family
comets.
