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ury the behaviour of the eentricity of rcury our tegrations is alitatively siilar to the results fro jaces laskars secular perturbation theory (eg eax&si; 035 over &si;&psn; 4 gyr) however， there are no apparent secular creases of eentricity or clation any orbital elents of the plas， which ay be revealed by still lonr-ter nurical tegrations we have al perford a uple of trial tegrations cdg otions of the outer five plas over the duration of &psn; 5 &tis; 1010 yr the result dicates that the three ajor renances the neptune–pto syste have been ataed over the 1011-yr ti-span

1 troduction

11defition of the proble

the estion of the stability of our lar syste has been debated over several hundred years， sce the era of newton the proble has attracted any fao atheaticians over the years and has played a central role the developnt of non-lear dynaics and 插os theory however， we do not yet have a defite answer to the estion of whether our lar syste is stable or not this is partly a result of the fact that the defition of the ter &l;stability&r; is vague when it is ed relation to the proble of plaary otion the lar syste actually it is not easy to give a clear， rigoro and physically angful defition of the stability of our lar syste

aong any defitions of stability， here we adopt the hill defition (gladan 1993): actually this is not a defition of stability， but of stability we defe a syste as beg unstable when a close enunter ours where the syste， star