Inadditiontothevaguenessoftheconceptofstability， theplanetsinourSolarsystemshowacharactertypicalofdynamicalchaos (Sussman & Wisdom1988， 1992).Thecauseofthischaoticbehaviourisnowpartlyunderstoodasbeingaresultofresonanceoverlapping (Murray & Holman1999; Lecar， Franklin & Holman2001).However， itwouldrequireintegratingoveranensembleofplanetarysystemsincludingallnineplanetsforaperiodcoveringseveral10Gyrtothoroughlyunderstandthelong-termevolutionofplanetaryorbits， sincechaoticdynamicalsystemsarecharacterizedbytheirstrongdependenceoninitialconditions.
Fromthatpointofview， manyofthepreviouslong-termnumericalintegrationsincludedonlytheouterfiveplanets (Sussman & Wisdom1988; Kinoshita & Nakai1996).， thelongestnumericalintegrationspublishedinjournalsarethoseofDuncan & Lissauer (1998).Althoughtheirmaintargetwastheeffectofpost-main-sequencesolarmasslossonthestabilityofplanetaryorbits， & Lissauer'spaper， ， theyfoundthatthecrossingtime-scaleofplanetaryorbits， whichcanbeatypicalindicatoroftheinstabilitytime-scale， ， thejovianplanetsremainstableover1010yr， & Lissaueralsoperformedfoursimilarexperimentsontheorbitalmotionofsevenplanets (VenustoNeptune)， ， butitseemsthattheterrestrialplanetsalsoremainstableduringtheintegrationperiod， maintainingalmostregularoscillations.
