Jupiter may have banished the ninth planet from our solar system, a recent study conducted by Canadian researchers at the University of Toronto has shown.
The findings were published on November 1 in the Astrophysical Journal, under the title “Could Jupiter or Saturn have ejected a fifth giant planet?”.
Astrophysicists based their research on prior theories circulated in 2011, which suggest that at the early beginnings of our solar system there were in fact 5 giant gas planets: Jupiter, Neptune, Uranus, Saturn and another planet which somehow got ejected from the group.
Ever since that time, research has been carried out to discover how it was possible to expel such a large planet, whose mass would’ve been similar to that of Neptune or Uranus. Usually, such events which make planets float freely through interstellar space tend occur due to close encounters between celestial objects.
One planet’s orbit is accelerated to such extent during these confrontations that it escapes from the Sun’s gravitational pull, leaving the planetary system and becoming a rogue planet.
It was believed that the most likely source for such an ejection taking place in our planetary system was either Saturn or Jupiter, but researchers had been undecided regarding which of the two was the actual culprit.
Now, Canadian astrophysicists aimed to discover the answer by taking into account factors that prior studies had omitted to investigate.
More precisely, they analyzed the probability of such an encounter, based on the consequences it would have had on smaller solar bodies, such as natural satellites and their orbits.
Their focus was on Callisto, the second largest moon of the planet Jupiter, and Iapetus, the third largest moon of Saturn.
Through computer simulations, researchers measured how likely it would’ve been for the two natural satellites to have their current orbit if their host planet had been the author of another celestial body’s ejection.
Such a dramatic event would’ve clearly disrupted the initial trajectories of these smaller objects, so the purpose was to discover whether Jupiter or Saturn could’ve pushed a planetary-mass object outside the solar system, and kept their moon orbiting like it does nowadays.
“Our evidence points to Jupiter”, declared Ryan Cloutier, lead author of the study, and PhD candidate at University of Toronto’s Department of Astronomy & Astrophysics.
As astrophysicists have shown, if Saturn had been the source of the ejection, Iapetus would’ve been “excessively unsettled”, and would have never reached the orbit it’s known to have now.
The possibility of Saturn causing another planet to become starless, while maintaining a natural satellite like Iapetus would’ve been of around 1%, experts have determined.
On the other hand, such an encounter between Jupiter and another giant planet would’ve caused some disturbance to Callisto, but eventually its orbit would’ve settled into the one that is still observable today.
According to the researchers, the likelihood of Jupiter banishing an ice giant and then maintaining a natural satellite having Callisto’s current trajectory has been estimated at 42%, which makes it quite possible that such an event really did take place approximately 4 billion years ago.
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