Scientists at the University of Toronto in Canada have discovered evidence pointing to a clash between Jupiter and another giant planet that could have resulted in the ejection of the latter from the Solar System around four billion years in the past.

The Solar System has long been known to contain only four massive gas planets in its roster of worlds: Neptune, Uranus, Saturn and Jupiter.

However, in 2011 a proposal was made that a fifth gas-filled planet could have also existed during the formation of the planetary system.

Astronomers have suspected that it was either Jupiter or Saturn that ousted the other planet.

In a study featured in The Astrophysical Journal, Ryan Cloutier and his colleagues at the University of Toronto explored the possibility of a titanic clash between some of the largest planets in the Solar System.

Ejections of planets typically occur when one of the planets begins to accelerate so fast and so often that it manages to break free from the Sun's powerful gravitational pull.

Previous studies on such celestial events, however, failed to consider the potential effects of massive planets ejections on minor objects, such as the moons of these giant planets as well as their own orbits.

To find out more about this planetary occurrence, the Toronto researchers created computer simulations using data on present-day trajectories of Jupiter's moon Callisto and Saturn's moon Iapetus.

The team then measured the probability of each moon producing its present orbit if its host planet suddenly gets involved in the ejection of a hypothetical planet. It is believed that such an incident would have generated significant disturbance to the original orbit of each moon.

"Ultimately, we found that Jupiter is capable of ejecting the fifth giant planet while retaining a moon with the orbit of Callisto," Cloutier said.

Regarding the possibility that Saturn was the one that kicked the other gas planet out of the Solar System, Cloutier explained that it would have been difficult for the ringed planet to do so because it would have unsettled the orbit of Iapetus too much, making it difficult for the moon to reconcile with its present-day trajectory.

Photo: NASA Goddard Space Flight Center | Flickr