Earth Could Collide With Other Planets

Everybody put on your helmet; Smivs writes "Astronomers calculate there is a tiny chance that Mars or Venus could collide with Earth — though it would not happen for at least a billion years. The finding comes from simulations to show how orbits of planets might evolve billions of years into the future. But the calculated chances of such events occurring are tiny. Writing in the journal Nature, a team led by Jacques Laskar shows there is also a chance Mercury could strike Venus and merge into a larger planet. Professor Laskar of the Paris Observatory and his colleagues also report that Mars might experience a close encounter with Jupiter — whose massive gravity could hurl the Red Planet out of our Solar System."

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Re:Or earth could turn into an elephant

[jeffb (2.718)]

From TFAbstract, helpfully linked downstream:

It has been established that, owing to the proximity of a resonance with Jupiter, Mercury's eccentricity can be pumped to values large enough to allow collision with Venus within 5 Gyr (refs 1â"3). This conclusion, however, was established either with averaged equations1, 2 that are not appropriate near the collisions or with non-relativistic models in which the resonance effect is greatly enhanced by a decrease of the perihelion velocity of Mercury2, 3. In these previous studies, the Earth's orbit was essentially unaffected. Here we report numerical simulations of the evolution of the Solar System over 5 Gyr, including contributions from the Moon and general relativity.

The authors claim this is the first extended simulation set incorporating GR and avoiding the problematic averaging technique.