We already knew Jupiter was the biggest planet in the solar system, but new research suggests it may also have been a bit of a bully. Canadian astronomers are now claiming that our solar system may have had another gas giant, before Jupiter came along and bumped it out of orbit.
According to Science Alert, the discovery was made using computer models and simulations, determining that the current shape of our solar system might have been influenced by a planetary expulsion. The orbits of Earth and Mars, in particular, would not be possible without having shared the solar system with another planet four billions of years ago.
The idea that there were once five gas giants in our solar system was proposed in 2011. This would include Jupiter, Saturn, Uranus, Neptune, and one other mystery planet. Either Saturn or Jupiter could have been responsible for ultimately booting it from the solar system, but Jupiter is the most likely perpetrator, according to a study published in The Astrophysical Journal.
To determine this, the researchers examined the orbits of Jupiter’s and Saturn’s moons. Using computer software, the team ran gravitational simulations to test if the orbits of the gas giant moons would end up at their current trajectory without Jupiter having thrown another planet out of the solar system. The probability suggests some massive planetary ejection did take place.
“Our evidence points to Jupiter,” said Ryan Cloutier from the University of Toronto, lead researcher in the study. “Ultimately, 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.”
Cloutier and his researchers calculated a 42 percent chance that Callisto, a moon of Jupiter, would be orbiting exactly as it is if Jupiter had bumped out another gas giant four billion years ago.
The team has described the celestial change as an “interplanetary chess game,” with Jupiter knocking the planet off the board.
Previous researchers who proposed a missing gas giant in 2011 did not consider the effect that a planetary ejection would have on Jupiter’s moons.
According to Science Daily, a planet can be expelled from a solar system when another planet orbits too close. With a gas giant as massive as Jupiter, it would be easy for the gravitational pull of one planet to cause the other to accelerate so fast that it breaks free from the pull of the sun. Essentially, Jupiter got close enough to this missing gas giant to launch it free from the solar system using a gravity slingshot.
Experts can never be sure what the missing planet was or where it is now, but astronomers already know that billions of exoplanets float through space freely, ejected long ago from their solar system.
“We do know that rogue planets roam the galaxy, and they were almost certainly ejected in this manner, so the idea of a lost solar system planet isn’t crazy,” astronomer Phil Plait wrote in Discover in 2011. “But it’s only one possible scenario.”
To see Phil Plait talk more about Jupiter and the solar system, watch the episode of Crash Course Astronomy below.
Do you think Jupiter is responsible for kicking a previous gas giant out of the solar system? What do you think the lost planet looks like and what would you have named it?
[Photo by NASA]