DYNAMICS OF PLANET CROSSING COMETS AND ASTEROIDS

The vicinity of the Earth is frequently visited by comets and small asteroids.  These small bodies travel on orbits with a dynamical lifetime much smaller than the age of the solar system, and therefore have to be replenished from suitable reservoirs. The main transport mechanisms from the source regions to Earth-crossing orbits are reviewed, also taking into account the many  theoretical and numerical results that have been recently obtained in this field.

A relatively  new development is the detailed analysis of the dynamics of asteroids which are currently on orbits that allow close Earth approaches. This is a challenging field, where observations, orbital determination and numerical integrations are used to improve our understanding of the dynamics of individual asteroids.