<P> Another project involved constructing the Digital Orrery by Gerry Sussman and his MIT group in 1988 . The group used a supercomputer to integrate the orbits of the outer planets over 845 million years (some 20 per cent of the age of the Solar System). In 1988, Sussman and Wisdom found data using the Orrery which revealed that Pluto's orbit shows signs of chaos, due in part to its peculiar resonance with Neptune . </P> <P> If Pluto's orbit is chaotic, then technically the whole Solar System is chaotic, because each body, even one as small as Pluto, affects the others to some extent through gravitational interactions . </P> <P> In 1989, Jacques Laskar of the Bureau des Longitudes in Paris published the results of his numerical integration of the Solar System over 200 million years . These were not the full equations of motion, but rather averaged equations along the lines of those used by Laplace . Laskar's work showed that the Earth's orbit (as well as the orbits of all the inner planets) is chaotic and that an error as small as 15 metres in measuring the position of the Earth today would make it impossible to predict where the Earth would be in its orbit in just over 100 million years' time . </P> <P> Jacques Laskar and his colleague Mickaël Gastineau in 2009 took a more thorough approach by directly simulating 2500 possible futures . Each of the 2500 cases has slightly different initial conditions: Mercury's position varies by about 1 metre between one simulation and the next . In 20 cases, Mercury goes into a dangerous orbit and often ends up colliding with Venus or plunging into the Sun . Moving in such a warped orbit, Mercury's gravity is more likely to shake other planets out of their settled paths: in one simulated case its perturbations sent Mars heading towards Earth . </P>

How many years does it take for planets to orbit the sun