▁this ▁means ▁that ▁the ▁position ▁of ▁a ▁planet ▁along ▁its ▁orbit ▁ultimately ▁becomes ▁impossible ▁to ▁predict ▁with ▁any ▁certain ty ▁( so , ▁for ▁example , ▁the ▁timing ▁of ▁winter ▁and ▁summer ▁become ▁uncertain ), ▁but ▁in ▁some ▁cases ▁the ▁or bits ▁themselves ▁may ▁change ▁dram atically . ▁Such ▁cha os ▁manifest s ▁most ▁strongly ▁as ▁changes ▁in ▁ecc ent ric ity , ▁with ▁some ▁plan ets ' ▁or bits ▁becoming ▁significantly ▁more — or ▁less — elli pt ical . ▁ ▁Ult imately , ▁the ▁Sol ar ▁System ▁is ▁stable ▁in ▁that ▁none ▁of ▁the ▁plan ets ▁are ▁likely ▁to ▁col lide ▁with ▁each ▁other ▁or ▁be ▁e ject ed ▁from ▁the ▁system ▁in ▁the ▁next ▁few ▁billion ▁years . ▁Bey ond ▁this , ▁within ▁five   b ill ion ▁years ▁or ▁so ▁Mars ' s ▁ecc ent ric ity ▁may ▁grow ▁to ▁around ▁ 0 . 2 , ▁such ▁that ▁it ▁lies ▁on ▁an ▁Earth - cross ing ▁orbit , ▁leading ▁to ▁a ▁potential ▁collision . ▁In ▁the ▁same ▁times c ale , ▁Mercur y ' s ▁ecc ent ric ity ▁may ▁grow ▁even ▁further , ▁and ▁a ▁close ▁encounter ▁with ▁Ven us ▁could ▁theoret ically ▁e ject ▁it ▁from ▁the ▁Sol ar ▁System ▁altogether ▁or ▁send ▁it ▁on ▁a ▁collision ▁course ▁with ▁Ven us ▁or ▁Earth . ▁This ▁could ▁happen ▁within ▁a ▁billion ▁years , ▁according ▁to ▁numerical ▁simulations ▁in ▁which ▁Mercur y ' s ▁orbit ▁is ▁pert urbed . ▁ ▁Moon – ring ▁systems ▁The ▁evolution ▁of ▁moon ▁systems