Dynamical effects of the Galaxy on the Oort's Cloud

The radial effects due to the Galaxy tide on some cometary nuclei of the Oort's Cloud are taken into account. We model the galactic structure by only considering the three components which are able to exert the main dynamic effects: the bulge, the disk and the dark halo. First we prove the stability role of the dark matter on a solar-type stellar orbit, either by numerical simulations or from the theoretical point of view. Then we simulate the orbital motions of some of the cometary nuclei which lie on the galactic plane at different longitude. The aim is to study the perturbations on the Keplerian orbits of these nuclei as soon as the whole galactic potential is switched. By assuming the solar distance from the Galaxy center as a parameter, a drastic reduction of the perihelions appears for some of them when the solar distance decreases. Finally the connection with the development of the Life inside the solar system is considered.