Formation and evolution of the Solar System eccentricity, with some planets' orbits becoming significantly more—or less—elliptical. Ultimately, the Solar System is stable in that none of the planets are likely to collide with each other or be ejected from the system in the next few billion years. Beyond this, within five billion years or so Mars's eccentricity may grow to around 0.2, such that it lies on an Earth-crossing orbit, leading to a potential collision. In the same timescale, Mercury's eccentricity may grow even further, and a close encounter with Venus could theoretically eject it from the Solar System altogether or send it on a collision course
Stability of the Solar System planets, it could substantially disrupt the Oort cloud which could cause major comet activity throughout the solar system. There are at least a dozen other stars that have a potential to make a close approach in the next few million years. Project LONGSTOP (Long-term Gravitational Study of the Outer Planets) was a 1982 international consortium of Solar System dynamicists led by Archie Roy. It involved creation of a model on a supercomputer, integrating the orbits of (only) the outer planets. Its results revealed several curious exchanges of energy between the outer planets, but no signs of gross instability. Another project