Jupiter Ousted a Fifth Gas Giant From Our Early Solar System

Jupiter ousted a fifth gas giant from our early solar system, according to new research on the matter conducted by astrophysicists with the University of Toronto.

Our solar system currently counts four giant planets: Neptune, Saturn, Uranus and Jupiter. A study released in the 2011 proposed that a fifth gas giant would have formed in the early stages of our solar system. Yet, it would have been shunned by another giant planet forcing the gravitational pull of the Sun.

With this in mind, Ph.D. candidate Ryan Cloutier and his colleagues set out to understand which of the two main suspects – Jupiter or Saturn – might have pushed the fifth gas giant out of the solar system four billion years ago.

According to Cloutier who is a Ph.D. candidate with the Astronomy and Astrophysics Department at the University of Toronto, all evidence points to Jupiter. When a planet is ousted, the process is a result of close planetary encounters. One of the two objects involved in the process accelerates the rotation to such a degree that it can pull out of the gravitational field exercised by the host star. Such a process should leave traceable marks of smaller celestial bodies. For instance, the orbit of the moons surrounding them.

The astrophysicists designed computer models that would simulate the orbit and trajectories of the two moons orbiting Saturn and Jupiter. Based on currently observed trajectories of Iapetus and Callisto, the computer models were designed to modify the trajectories according to hypothetical data triggered by the possibility that either Saturn or Jupiter broke free of the Sun’s gravitational pull.

The results of the study, featuring in the latest issue of the Astrophysical Journal indicate that Jupiter ousted a fifth gas giant from our early solar system. The likelihood that Jupiter is the planet ejecting the other gas giant was given away by its moon, Callisto. Such a major event as a highly accelerated spin coupled with the breaking away from the gravitational pull of the Sun would generate a massive disturbance to the moon’s orbit.

“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”,

explained Cloutier.

With Jupiter, things are different. While it would have been capable of ejecting a fifth gas giant from our early solar system, it would also be able to retain a moon displaying the same orbit as Callisto.

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