MEGNO: fast method to study dynamics of planetary systems

In this work we introduce the fast chaos indicator MEGNO (Mean Exponential Growth factor of Nearby orbits). This technique is widespread for studying of the dynamical behaviour of planetary system in the framework of the gravitational N-body problem.We present some examples in both Solar System and exoplanetary systems and we show some of our last results for the Luyten's system, the closest multi-planetary system known to us so far.