How Did Jupiter Shape Our Solar System?


Jupiter hasn’t always been in the same place in our solar system. Early in the history of our solar system, Jupiter moved inward towards the sun, almost to where Mars currently orbits now, and then back out to its current position.

The migration through our solar system of Jupiter had some major effects on our solar system. Some of the effects of Jupiter’s wanderings include effects on the asteroid belt and the stunted growth of Mars.

What other effects did Jupiter’s migration have on the early solar system and how did scientists make this discovery?

In a research paper published in the July 14th issue of Nature, First author Kevin Walsh and his team created a model of the early solar system which helps explain Jupiter’s migration. The team’s model shows that Jupiter formed at a distance of around 3.5 A.U (Jupiter is currently just over 5 A.U from the sun) and was pulled inward by currents in the gas clouds that still surrounded the sun at the time. Over time, Jupiter moved inward slowly, nearly reaching the same distance from the sun as the current orbit of Mars, which hadn’t formed yet.

“We theorize that Jupiter stopped migrating toward the sun because of Saturn,” said Avi Mandell, one of the paper’s co-authors. The team’s data showed that Jupiter and Saturn both migrated inward and then outward. In the case of Jupiter, the gas giant settled into its current orbit at just over 5 a.u. Saturn ended its initial outward movement at around 7 A.U, but later moved even further to its current position around 9.5 A.U.

Astronomers have had long-standing questions regarding the mixed composition of the asteroid belt, which includes rocky and icy bodies. One other puzzle of our solar system’s evolution is what caused Mars to not develop to a size comparable to Earth or Venus.

Artist's conception of early planetary formation from gas and dust around a young star. Image Credit: NASA/JPL-Caltech

Regarding the asteroid belt, Mandell explained, “Jupiter’s migration process was slow, so when it neared the asteroid belt, it was not a violent collision but more of a do-si-do, with Jupiter deflecting the objects and essentially switching places with the asteroid belt.”

Jupiter’s slow movement caused more of a gentle “nudging” of the asteroid belt when it passed through on its inward movement. When Jupiter moved back outward, the planet moved past the location it originally formed. One side-effect of caused by Jupiter moving further out from its original formation area is that it entered the region of our early solar system where icy objects were. Jupiter pushed many of the icy objects inward towards the sun, causing them to end up in the asteroid belt.

“With the Grand Tack model, we actually set out to explain the formation of a small Mars, and in doing so, we had to account for the asteroid belt,” said Walsh. “To our surprise, the model’s explanation of the asteroid belt became one of the nicest results and helps us understand that region better than we did before.”

With regards to Mars, in theory Mars should have had a larger supply gas and dust, having formed further from the sun than Earth. If the model Walsh and his team developed is correct, Jupiter foray into the inner solar system would have scattered the material around 1.5 A.U.

Mandell added, “Why Mars is so small has been the unsolvable problem in the formation of our solar system. It was the team’s initial motivation for developing a new model of the formation of the solar system.”

An interesting scenario unfolds with Jupiter scattering material between 1 and 1.5 AU. Instead of the higher concentration of planet-building materials being further out, the high concentration led to Earth and Venus forming in a material-rich region.

The model Walsh and his team developed brings new insight into the relationship between the inner planets, our asteroid belt and Jupiter. The knowledge learned not only will allow scientists to better understand our solar system, but helps explain the formation of planets in other star systems. Walsh also mentioned, “Knowing that our own planets moved around a lot in the past makes our solar system much more like our neighbors than we previously thought. We’re not an outlier anymore.”

If you’d like to access the paper (subscription or paid/university access required), you can do so at:

Source: NASA Solar System News, Nature

25 Replies to “How Did Jupiter Shape Our Solar System?”

  1. Reading this article one get the impression that it is common knowledge that Jupiter moved about several billion years ago. This must only be a theory. How can astronomers know how the planets moved so long ago?

    1. Ubbe, In studying other star systems, we see evidence of gas giants that have migrated inward towards their host star. Basically Walsh and his team created a model that used the evidence we have of planetary migration in our solar system. Walsh’s model provided data that supports what is believed to have happened.

      1. Yo Ray, it should be its, not “it’s”, at the first paragraph, third line, and also at the fifth paragraph, third and fourth lines.

    2. “Only” a theory? One scientific theory can be worth a thousand facts! A valid theory is a super-fact, as it is based on many facts and predicts all of them and more correctly. A puny fact can only be tested on its own observations, a grand theory can be tested on all of them.

      Especially the basic Nice model, without the Grand Tack and observations of many migrated exoplanets (from orbital dynamics), is one massively predictive model. I was truly impressed when I first heard of it.

      A short list of its predictions (see the link) would be:

      – The large orbital radius and eccentricities of the outer planets. (Compare with Kepler’s compact and flat many-planet systems.)
      – The Late Heavy Bombardment!
      – The “libration angle, eccentricity and the large inclinations of the orbits” of Jovian and Neptune Trojans.
      – Some of the asteroid belt properties (capture and erosion of outer belt).
      – Capture and retention of outer system satellites.
      – Some of the Kuiper belt properties (scattering and “hot” bodies).
      – Oort cloud!

      I am sure there are other things to put there.

      This follows basically the same method that biologists use to constrain sets of historical pathways actually taken by populations when they parse phylogenetic trees. The most predictive models “win”.

      Now exoplanets and Grand Tack add to the testing and resolution of detail, in the same way that finding more detail does for biology (using more fossils or sequenced genomes).

      1. Ok, no need to loose your temper. I meant nothing ill to a theory. I was just pointing out that this article makes it sound like this is the one and only theory worth mentioning. There must be other theories on why Mars didn´t get as big as Earth and Venus. I have for example heard theories about Mars being affected by the cataclysmic event which created the asteroid belt.

        @Torbjörn & Ray: Good point about other systems development. I don´t argue the fact that the planet have been moving. It is just that when reading the article you get the impression the we already know exactly in which way.

      2. I am sorry if I come over as loosing my temper! I wanted to make emphasis, as in the previous sentence.

  2. If you’d like to access the paper (subscription or paid/university access required), you can do so at…

    Screw that… you can get the free paper (PDF) here.

    1. Ivan, I tried looking on Arxiv, for a free version of the paper. I’m not entirely sure the link you posted is supposed to be public, which is why I didn’t include it in the article.

    1. Matt, I don’t have any data on that. You could contact the authors of the paper, as that is an EXCELLENT question to ask them. I do know, based on the model used, Mars hadn’t formed yet.

      1. On page 2 of the paper, and to the right of Figure 2, it states:

        The present-day asteroid belt is expected to have had its eccentricities and inclinations reshuffled during the so-called late heavy bombardment (LHB); the final orbital distribution in our simulations matches the conditions required by LHB models.

      2. The next step — perhaps beyond the scope of the paper — would be to compare the composition and isotope mix of what we know of the LHB objects to what would be expected from the reshufflings in this model. Perhaps, also, we can get a clearer idea of the percentage of the LHB’s contribution, if any, to Earth’s hydrosphere.

      3. Which is why we need to send more robotic sample-return missions to the Moon and to the asteroid belt.

  3. I have just looked at the paper, so I have not looked at the guts of this. However, one clear question stands out in my mind. If the orbits first migrated in and then further out from where they started this means there is a lot of gravitational potential energy

    ?? = -GMm(1/r – 1/r_0), r_0 > r,

    conferred to these gas giants. The gravitational system is essentially conservative, so this energy came from somewhere. In other words as the gas giants were migrating out there had to be a net bulk of material that migrated in. There is some modeling of rocky material which moved in, but this is about 10^{-2} the bulk mass of the jovians. As a result something does not seem to balance, unless a Jupiter equivalent of matter fell into the sun.


    1. At the final paragraph of the paper, in the last sentence, the authors state that the “difference between [the] Solar System and the currently known extrasolar systems is that, according to our results, Jupiter ‘tacked’ at 1.5 AU and then migrated outward, owing to the presence of Saturn.”

      1. All of the gas giants tracked outwards, which means all of their gravitational potential energies increased. This is surprising. I would not be surprised if Jupiter migrated out and Saturn inwards. The question is where did all of this energy come from?


      2. According to the Nice model description (incidentally, one of the authors of the above paper, Alessandro Morbidelli, is also one of the authors of the Nice model), planetesimals in the protoplanetary disc’s inner edge exchange angular momentum with the gas giants, so that the gas giant planets move outwards, while the planetesimals move inwards, preserving the angular momentum of the system. Despite the minute movement that each exchange of momentum can produce, these accumulate over hundreds of millions of years and shift (migrate) the orbits of the gas giant planets by significant amounts. These gas giant planets then plough into the outer planetesimal disc of the early Solar System, scattering tens of thousands of planetesimals from their formerly stable orbits. This disruption almost entirely scatters the primordial disc and removing 99% of its mass; consequently, some of the planetesimals are thrown into the inner Solar System, producing a sudden influx of impacts on the terrestrial planets: the Late Heavy Bombardment.

      3. Indeed! Yet another example that there is no such thing as “free energy” — there is always a trade off somewhere!

  4. Great Article! Fascinating area to study.
    They should also discuss the fact that Uranus and Neptune formed between Jupiter and Saturn originally also (and switched positions) and that is why we have such a scattered mess of a Kuiper belt (and Pluto’s goofy orbit). The more we learn about this stage of the Solar System formation, the better we understand the outer planets.
    Uranus and Neptune never get much respect………

  5. “We’re not an outlier anymore.”

    I am glad a professional astronomer states what “we all” (i.e. I) think. =D

    As for the model, I think it means that when Kepler can resolve the habitable zone of Sun analogs, it will see systems that looks like ours. I also hopes it predicts the scant water on Venus, Earth, Mars, since it ups the likelihood of Earth analogs vs water worlds.

    Sure water is the most productive biosphere environment, and it is surprisingly diverse ecologically according to Venter’s mass sequencing of “environmental genomes”. At the same time I can’t help thinking that our few thousands of percent of water is “just right” for advanced technological societies.

    Btw, wouldn’t the Grand Tack timeline fit very nicely with the recent hypothesis of a fast protoplanetary Mars aggregation (of some 3 Ma)? While remaining bulkier terrestrial planets “require an additional ~ 30 Myr to complete their accretion.” [I’m using Ivan’s unofficial link.]

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