From the Lab: French researchers uncover why solar system planets are unlikely to collide

More than 30 years ago researchers discovered that the orbits of the four terrestrial planets in our solar system - Mercury, Venus, Earth and Mars - are chaotic. Despite this behaviour, French researchers believe their orbits are stable and the chances of a planetary collision are slim.

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Researchers from the Observatoire de Paris recently published a paper on the stability of the orbits of the terrestrial planets of our solar system. © Dhananjay Khadilkar

The researchers from the Observatoire de Paris - PSL and CNRS are now able to show why.

"Computer simulations show that the probability of a catastrophic event such as a plantery collision is unexpectedly low - just one chance in 100 over the next five billion years," lead study author Federico Mogavero told RFI.

"This is a very long time scale comparable to the age of the solar system (and to the remaining lifetime of the Sun)."

Mogavero said the origin of the chaotic behaviour lies in the existence  of the gravitational interactions between the planets.

He and his colleagues arrived at their conclusions after developing a simplified and realistic model of how the orbits of the planet will evolve over long periods of time.

"The essential idea here is to forget about the precise position of the planets around the Sun and to focus on how the elliptical orbits will change the orientation and shape over time."

Mogavero said that over the next hundreds of millions of years, the random changes in the orbits of the planets "will be mostly directed along safe directions, which will keep the planets far from a catastrophic event."