A FORCE known as orbital chaos may cause our solar system to go haywire, leading to a possible collision between earth and Venus or Mars, according to a study released today.
The good news is that the likelihood of such a smash-up is small, around one-in-2500.
And even if the planets did careen into one another, it would not happen before another 3.5 billion years.
Indeed, there is a 99 per cent chance that the sun's posse of planets will continue to circle in an orderly pattern throughout the expected life span of our life-giving star, another five billion years, the study found.
After that, the sun will likely expand into a red giant, engulfing earth and its other inner planets - Mercury, Venus and Mars - in the process.
Astronomers have long been able to calculate the movement of planets with great accuracy hundreds, even thousands of years in advance. This is how eclipses have been predicted.
But peering further into the future of celestial mechanics with exactitude is still beyond our reach, said Jacques Laskar, a researcher at the Observatoire de Paris and lead author of the study.
"The most precise long-term solutions for the orbital motion of the solar system are not valid over more than a few tens of millions of years," he said.
Using powerful computers, Mr Laskar and colleague Mickael Gastineau generated numerical simulations of orbital instability over the next five billion years.
Unlike previous models, they took into account Albert Einstein's theory of general relativity. Over a short time span, this made little difference, but over the long haul it resulted in dramatically different orbital paths.
The researchers looked at 2501 possible scenarios, 25 of which ended with a severely disrupted solar system.