Moon Callisto Reveals Mighty Jupiter Set A Gas Giant Free From Early Solar System - For Good!

Peter R
October 31, 2015 01:17 PM EDT

Looking at the orbit of Jupiter's moon Callisto, researchers have concluded that the planet kicked another gas giant out of the solar system some 4 billion years ago.

According to UPI, the possibility that another gas giant existed in the solar system in addition to the four present now, has been in strong reckoning for a while. It was believed that either Saturn or Jupiter came too close to the fifth gas giant and sent it spiraling in space. Such interactions between large planets are known to cause planets to break from a star's gravity.

Researchers at University of Toronto zeroed on Jupiter after analyzing the orbits of its moons and that of Saturn. Their analysis showed that only Jupiter could have ejected a gas giant while retaining a moon with the orbit of Callisto.

"We found that Jupiter is capable of ejecting the fifth giant planet while retaining a moon with the orbit of Callisto. On the other hand, it would have been very difficult for Saturn to do so because Iapetus would have been excessively unsettled, resulting in an orbit that is difficult to reconcile with its current trajectory," said Ryan Cloutier, the study's lead author.

The findings also fit with early computer models for the solar system, which can be explained better when a fifth giant planet is assumed to have existed. And where is missing planet? It could be anywhere.

Jupiter's escapade has been described in The Astrophysical Journal.