The researchers carried out 2,500 tests and, in some, the outcome was Earth being involved in a collosion with Mars or Venus. The tests also showed that there was a chance that Mercury could collide with Venus creating a larger planet and that Mars could have a close encounter with Jupiter which would push it out of our Solar System.
Speaking of the collision and other results of the tests Professor Laskar said...
"It will be complete devastation," said Professor Laskar.
"The planet is coming in at 10km per second - 10 times the speed of a bullet - and of course Mars is much more massive than a bullet."
Professor Laskar's calculations also show that there is a possibility of Mercury crashing into Venus. But in that scenario, the Earth would not be significantly affected.
"If there is anyone around billions of years from now, they'd see a burst of light in the sky and the two planets would be merged," he said.
"The new planet would be a little bit bigger than Venus, and the Solar System would be a little more regular after the collision, but the Earth's orbit would not be affected."
For a slightly different view on worlds colliding - the whole of the movie 'When Worlds Collide' is on you tube. This is part one of nine - click through on the vid and the links to all nine parts are there.