Computer simulation shows Solar System once had an extra planet

Sep 22, 2011 by Deborah Braconnier report
The orbit histories of giant planets in one of the simulation with five initial planets. Image credit: arXiv:1109.2949v1 [astro-ph.EP]

( -- A new study published on shows that, based on computer simulations, Jupiter, Saturn, Uranus and Neptune may not have been the only gas giants in our solar system. According to David Nesvorny from Colorado’s Southwest Research Institute, our current solar system could never have happened without the existence of a fifth planet.

In an effort to determine just how the was formed, Nesvorny performed a series of some 6,000 . When using just the four giant planets, every simulation found that they were too large and ended up destroying each other. In the simulations where they did manage to make it in one piece, the rocky planets such as Mars and Venus, were instead destroyed. According to his results, the current solar system structure would have a very low probability of occurring if it started with only four rocky planets and four gas planets.

After running these simulations, Nesvorny decided to add a fifth large planet into the mix. With the addition of this large planet, results found that the odds of our current solar system increased significantly.

The most successful simulations show that Jupiter, Saturn, Uranus, Neptune and a fifth planet, similar to that of Neptune or Uranus, started out all tightly packed and orbiting some 15 times further from the sun then our planet Earth. The lighter planets are sent out further by Jupiter and . A close encounter with then ejects this mysterious fifth planet out of the solar system.

Recent discoveries of free-floating planets in interstellar space show that the ejection of planets could have been common, according to the study.

Explore further: Quest for extraterrestrial life not over, experts say

More information: Young Solar System's Fifth Giant Planet? arXiv:1109.2949v1 [astro-ph.EP]

Recent studies of solar system formation suggest that the solar system's giant planets formed and migrated in the protoplanetary disk to reach resonant orbits with all planets inside 15 AU from the Sun. After the gas disk's dispersal, Uranus and Neptune were likely scattered by gas giants, and approached their current orbits while dispersing the transplanetary disk of planetesimals, whose remains survived to this time in the region known as the Kuiper belt. Here we performed N-body integrations of the scattering phase between giant planets in an attempt to determine which initial states are plausible. We found that the dynamical simulations starting with a resonant system of four giant planets have a low success rate in matching the present orbits of giant planets, and various other constraints (e.g., survival of the terrestrial planets). The dynamical evolution is typically too violent, if Jupiter and Saturn start in the 3:2 resonance, and leads to final systems with fewer than four planets. Several initial states stand out in that they show a relatively large likelihood of success in matching the constraints. Some of the statistically best results were obtained when assuming that the solar system initially had five giant planets and one ice giant, with the mass comparable to that of Uranus and Neptune, was ejected to interstellar space by Jupiter. This possibility appears to be conceivable in view of the recent discovery of a large number free-floating planets in interstellar space, which indicates that planet ejection should be common.

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User comments : 13

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3.4 / 5 (14) Sep 22, 2011
Of course we had an extra planet, it was called Pluto we lost it in 2006 ;)
2.9 / 5 (7) Sep 22, 2011
planet X from 1950s B movies exists.. who knew!
3 / 5 (4) Sep 22, 2011
To be expected I have a third superfluous nipple, but I'm not telling you where.

"Recent discoveries of free-floating planets in interstellar space show that the ejection of planets could have been common,'
So it's not happening anymore?
4.2 / 5 (5) Sep 22, 2011
Aha! They've found the dread Nibiru! (Well, they found where it *started*...but where is it now?!)
5 / 5 (2) Sep 22, 2011
Has this study been peer-reviewed? The original posting on the arXiv website doesn't say so, so I would be rather careful in reporting such claims without further scrutiny.
2.8 / 5 (4) Sep 22, 2011
This just in, computer simulations show computer simulations can show anything.
2.6 / 5 (5) Sep 22, 2011
I don't think that this X planet would be outright ejected out of the solar system, most likely will be in a highly elliptical orbit, and would eventually return.
1.7 / 5 (6) Sep 23, 2011
this is what i love about simulations. you never know what to expect!!!!

considering we obviously do not yet understand all of gravity dynamics, i would say it's premature to put all your science faith in simulations of this sort, or most sorts, particularly in proportion to the number and degree of variance of the variables in the system ( climate being an obvious candidate---and i'm not denier----)

i'm not going to believe in a 10th planet, nor am i going to believe anyone telling me about 5 feet of global ocean rise in 100 years or any other crappy hyper specific prediction about a massive piece of reality changing. just because of an accumulated 'simulation'. unless there is a something experimental to back your finding. if at least indirectly ( like if you could say the same rules of simulation were used to make a prediction about a group of asteroids, which was confirmed by observation ).
otherwise is this not an exercise in speculation?
2.8 / 5 (4) Sep 23, 2011
Speculation is how most science gets started though.
5 / 5 (2) Sep 24, 2011

I just remembered Bode's "Law"!!

1 / 5 (3) Sep 25, 2011
Of course Sol had additional planets. A Mars size planet supposedly smacked into Earth to make Luna (the moon), didn't it? Just because it isn't here today, doesn't mean it never existed.

Here's an interesting Q&A about Sol's major planets having (apparently unusually) circular orbits.

As a cool aside: Did you all know that technically, Sol and Jupiter form a binary system? That is, the center of mass between the two lies outside the volume of the sun (but just a little).
not rated yet Oct 05, 2011
Has anyone mentioned the possiblity of our asteriod belt being the reminisces of this fifth planet? Considering that option, studying the composites of that material to the possiblity of a once existing planet would be an amazing discovery to its genetic makeup and so forth. Just saying :/
1 / 5 (2) Oct 05, 2011
center of mass between the two lies outside the volume of the sun
IMO it drives the solar plasma flow with Corriolis force, switches solar cycles and probably it affects climate on the Earth up to certain level.

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