Celletti A., Chessa A. , Hadjidemetriou J., Valsecchi G.B. A systematic study of the stability of symmetric periodic orbits in the planar, circular, restricted three-body problem (964K, Postcript) ABSTRACT. We investigate symmetric periodic orbits in the framework of the planar, circular, restricted, three-body problem. Having fixed the mass of the primary equal to that of Jupiter, we determine the linear stability of a number of periodic orbits for different values of the eccentricity. A systematic study of internal resonances, with frequency $p/q$ with $2\leq p\leq 9$, $1\leq q\leq 5$ and $4/3\leq p/q\leq 5$, offers an overall picture of the stability character of inner orbits. For each resonance we compute the stability of the two possible periodic orbits. A similar analysis is performed for some external periodic orbits. Furthermore, we let the mass of the primary vary and we study the linear stability of the main resonances as a function of the eccentricity and of the mass of the primary. These results lead to interesting conclusions about the stability of exosolar planetary systems. In particular, we study the stability of Earth-like planets in the planetary systems HD168746, GI86, 47UMa,b and HD10697.