Introduction

Abstract

It is generally agreed that planets are the cosmic wombs where life may start and develop, sheltered in the hospitable, rich in nutrients, protective environments of certain planets. Though other alternatives can not be completely excluded, the physics, chemistry, and the abundances of chemical elements, strongly concur in favor of a planetary origin of life. This makes the search for extrasolar planetary systems the first step in the search from extraterrestrial life, but unfortunately we do not yet know whether a planetary system like ours represents a rarity or a common occurance among the billions of stars of our Galaxy. The reason is that the detection of planets around other stars is technically a very difficult problem, something like trying to see a firefly flying near the edge of a powerful searchlight.