Nice_model - Wikiparency

# Nice model  **Microsim — three.js (Wikitube framework):** *Rock inside, gas and ice outside (Solar System explorer)* <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/solar/Solar_System.html?view=composition&embed=1" data-title="Rock inside, gas and ice outside (Solar System explorer)"></div> *The Solar System explorer locked on this article's state (`?view=composition`); every object and population of the [[PORTAL_Solar_System|Solar System portal]] has its own state in the same scene.*  *Try: press l to show the labels and find the four giants from Jupiter out to Neptune, the planets whose orbits the Nice model rearranges; drag to a view from above to compare their present spacing, which the model builds from a compact start; then press o to hide the orbits and set the speed to 100 years/s to watch Jupiter complete about five circuits for every two of Saturn's.* The **Nice model** is a scenario for the dynamical history of the Solar System in which the giant planets [[Jupiter]], [[Saturn]], [[Uranus]] and [[Neptune]] formed on a compact, nearly circular set of orbits and later moved to their present ones through an instability, driven by their interactions with a massive disc of leftover planetesimals.[^tsiganis2005] It takes its name from the city of Nice in France, at whose Observatoire de la Côte d'Azur it was developed, and it was set out in three papers published together in *Nature* in 2005.[^tsiganis2005][^morbidelli2005][^gomes2005] The model was designed to explain the orbits of the giant planets and was extended to account for the [[Late_Heavy_Bombardment|Late Heavy Bombardment]], the capture of the [[Jupiter_trojan|Jupiter trojans]], the irregular moons of the giant planets, and the structure of the [[Kuiper_belt|Kuiper belt]], [[Scattered_disc|scattered disc]] and [[Oort_cloud|Oort cloud]].[^levison2008] Discrepancies with observations have produced several revisions, including the Nice 2 model, the "jumping-Jupiter" variant, and a version with five giant planets.[^levison2011][^nesvorny2011] The explorer at the top of this page shows the Solar System's present composition, with the four giants outside the [[Frost_line_(astrophysics)|frost line]]; the Nice model is an account of how those four arrived where the explorer draws them. ## Description In the original model the gas of the [[Protoplanetary_disk|protoplanetary disk]] had already dispersed, leaving the four giants on near-circular orbits between about 5.5 and 17 [[Astronomical_unit|AU]], much closer together than today, and beyond them a disc of rocky and icy planetesimals of about 35 Earth masses reaching to about 35 AU.[^tsiganis2005] For comparison, Uranus and Neptune now orbit at 19.2 and 30.1 AU.[^jpl-t1] By [[Kepler's_laws_of_planetary_motion|Kepler's third law]] an orbit at 17 AU takes 17^1.5 ≈ 70 years, against Neptune's present 165 years (derived). The planets migrate by trading orbital energy and [[Angular_momentum|angular momentum]] with the planetesimals. The outermost giant scatters most of the small bodies it meets inward and recoils outward. Those bodies then meet the next planet in, which does the same, so the outer three giants drift outward one encounter at a time, each shift tiny but the sum large. Jupiter, the innermost and most massive, is different: it throws planetesimals onto very elongated orbits or out of the Solar System entirely, and the energy that costs moves it slightly inward.[^tsiganis2005][^levison2008] The slow migration continues for hundreds of millions of years, until Jupiter and Saturn, diverging, cross their 1:2 mean-motion [[Resonance|resonance]], where Saturn's period is exactly twice Jupiter's. Today the ratio is 29.42 / 11.86 ≈ 2.48 (derived), so the crossing lies in the past.[^nasa-fs] At the resonance the two planets' eccentricities jump and the system destabilises. Saturn's more eccentric orbit brings it into encounters with the ice giants, which are thrown onto eccentric orbits of their own and plough into the planetesimal disc, scattering it and removing about 99% of its mass.[^tsiganis2005] Dynamical friction with the remaining planetesimals then damps the ice giants' eccentricities, leaving Uranus and Neptune on near-circular orbits again.[^levison2008] In about half of the original simulations the two ice giants exchange places, so that the planet now outermost began inside the other.[^tsiganis2005] Such fractions describe a set of chaotic runs rather than a probability for the real Solar System, and simulations of this kind are sensitive to round-off and time-step errors.[^boekholt2015] ## Solar System features Because the early Solar System cannot be observed directly, a dynamical model is judged by how well the small-body populations it produces match those seen today.[^hansen2005] The Nice model reproduces many features, but no single set of initial conditions reproduces all of them, and a model that needs different starting points to explain different populations is weaker for it, since the Solar System had only one history. ### The Late Heavy Bombardment A central aim of the model was to explain the [[Late_Heavy_Bombardment|Late Heavy Bombardment]], a proposed surge of impacts on the [[Moon]] and the terrestrial planets several hundred million years after the planets formed. In the model the instability produces it in two parts: icy planetesimals from the disrupted outer disc arrive first, in a sharp spike, while resonances sweeping through the [[Asteroid_belt|asteroid belt]] drive asteroids onto planet-crossing orbits for longer, removing about 90% of the belt's mass. The number of bodies reaching the Moon matches the lunar crater record.[^gomes2005] The same impacts would have melted the interior of [[Ganymede_(moon)|Ganymede]] and separated its ice from its rock, but not that of [[Callisto_(moon)|Callisto]], which lies farther from Jupiter and is struck at lower speeds; that would explain why one moon is differentiated and the other largely is not.[^baldwin2010] The same flux would have boiled away too much ice from Saturn's inner moons, however.[^nimmo2012] The bombardment itself is now in doubt. Re-examinations of lunar crater ages find a steady decline in impacts rather than a peak, and suggest that the apparent spike arises from the uncertainties of dating combined with the age limit of the lunar crust.[^harrison2018] Argon-40/argon-39 dating on the asteroid [[4_Vesta|Vesta]] also argues against a late cataclysm.[^cartwright2022] Doubts about the bombardment weaken one of the model's original motivations, though not its account of the giant planets' orbits. ### Trojans and the asteroid belt Jupiter's trojans share its orbit around the L4 and L5 Lagrange points, 60° ahead of and behind the planet. As Jupiter and Saturn approach and then leave the 2:1 resonance, the slow circulation of their mutual conjunctions can match the trojans' own libration period, and the trojan region becomes dynamically open: existing trojans escape and objects from the scattered disc wander in. Once the planets move apart the region closes again and traps the newcomers.[^morbidelli2005] The captured population has the wide spread of inclinations seen in real Jupiter trojans, previously unexplained, and the same mechanism supplies Neptune's trojans.[^morbidelli2005][^crida2009] Planetesimals caught in Jupiter's resonances as it migrated inward may also have been implanted in the outer asteroid belt, beyond about 2.6 AU, and in the 3:2 resonance that holds the [[Hilda_asteroid|Hilda asteroids]].[^levison2009] Collisional grinding, followed by drift into unstable resonances, would have removed more than 90% of the implanted mass, and the surviving size distribution matches the observed one, suggesting that the trojans, Hildas and dark D-type asteroids of the outer belt are captured outer-disc planetesimals.[^bottke2008] D-type asteroids found closer than 2.5 AU are harder for the original model to explain.[^demeo2014] ### Outer-system satellites The giant planets' irregular moons, small bodies on distant, inclined and often retrograde orbits, pose a problem: any captured before the instability would have been stripped away during the planetary encounters. In the Nice model new ones are captured during those encounters, when a planetesimal passing close to two planets at once can lose enough energy to be bound to one of them; for an ice giant the chance per planetesimal is small, but so many planetesimals pass that the observed populations can be built.[^nesvorny2007] The captured orbits match the observed semi-major axes, inclinations and eccentricities of the irregular moons of Saturn, Uranus and Neptune, and later collisions among them would explain their collisional families and their present size distribution.[^nesvorny2007][^nesvorny2004][^bottke2010] Neptune's large moon [[Triton_(moon)|Triton]] fits a different route, capture by breaking up a binary pair during an encounter.[^agnor2006][^vokrouhlicky2008] The original simulations did not give Jupiter enough encounters to capture its own irregular moons.[^nesvorny2007] ### Formation of the Kuiper belt In the model the Kuiper belt began denser and closer to the Sun, with its outer edge near 30 AU, just beyond ice giants that orbited at perhaps 15–20 AU.[^gomes2005][^levison2008] During the instability Neptune is thrown into the disc on an orbit with a semi-major axis near 28 AU and an eccentricity as high as 0.4. Its resonances then overlap, the region out to its 2:1 resonance becomes chaotic, and planetesimals diffuse outward. When Neptune's eccentricity is damped they are left on stable orbits: those that met Neptune only briefly keep low inclinations and form a dynamically cold belt, while those scattered and caught in its resonances for longer end on hotter orbits, some remaining as resonant objects such as [[Pluto]] and the other plutinos.[^levison2008] This produces an outer edge at Neptune's 2:1 resonance and a belt with a tiny fraction of the original mass. It does not match everything. The model gives classical Kuiper belt objects a mean eccentricity of 0.10–0.13 against the observed 0.07, too few high-inclination objects, and no explanation for the complete absence of grey objects in the cold population.[^levison2008] The cold [[Classical_Kuiper_belt_object|classical objects]] are redder than the hot ones and include many wide binaries that would not survive a close pass by Neptune, suggesting that they formed where they are.[^levison2008][^lovett2010] Preserving them requires Neptune's eccentricity to stay small, or its orbit to precess rapidly through interaction with Uranus.[^wolff2012][^batygin2011] ### Scattered disc and Oort cloud Objects that Neptune threw beyond about 50 AU could be caught in its distant resonances, or, if their eccentricities fell while in resonance, escape onto stable orbits of the [[Scattered_disc|scattered disc]]. While Neptune's orbit was still eccentric its aphelion reached well beyond its present distance, and bodies whose perihelia were raised near that point were left detached when Neptune's orbit circularised.[^levison2008] Bodies thrown out to around 5,000 AU could have their perihelia lifted by the galactic tide, forming the inner [[Oort_cloud|Oort cloud]], and those thrown farther were randomised by passing stars into the spherical outer cloud; bodies scattered by Jupiter and Saturn were mostly ejected.[^dones2004] A few per cent of the original disc ends in these reservoirs.[^brasser2013] ## Modifications Later work changed the model in two main ways. The first concerns its starting point. Hydrodynamic simulations of giant planets embedded in the gas disc show that they migrate inward, as the hot Jupiters of other systems appear to have done; Jupiter's inward drift in the Solar System would have been halted when Saturn was captured into resonance with it, and the other planets would then have been captured too, leaving the four giants in a chain of resonances with Jupiter and Saturn in 3:2.[^morbidelli2007] The Nice 2 model starts from that chain. Gravitational stirring by Pluto-mass bodies in the outer disc slowly draws the giants inward and breaks the chain, and a late instability like the original follows; its timing no longer depends on fine-tuning the distance between the outer planet and the disc.[^levison2011] The second modification answers problems in the inner Solar System. If Jupiter and Saturn separate smoothly, their secular resonances sweep slowly through the inner system, pumping up the eccentricities of the terrestrial planets and possibly destabilising them, and they leave too many high-inclination asteroids.[^brasser2009][^morbidelli2010] In the jumping-Jupiter scenario an ice giant is scattered inward by Saturn, encounters Jupiter, and is thrown outward again; Saturn's orbit expands and Jupiter's shrinks in steps, so the resonances jump past the inner planets and the belt instead of sweeping across them.[^brasser2009][^morbidelli2010] The encounters also let Jupiter capture irregular moons and trojans, with one trojan swarm depleted relative to the other if the ice giant crosses it.[^nesvorny2014][^nesvorny2013] In this version the main rocky impactors of any late bombardment come from an inner extension of the asteroid belt, of which the Hungaria asteroids are a remnant, and some D-type asteroids reach the inner belt while the ice giant crosses it.[^bottke2012][^vokrouhlicky2016] ## Five-planet Nice model Simulations of the jumping-Jupiter scenario often eject the ice giant that encounters Jupiter, losing a planet the Solar System still has. David Nesvorný and others therefore proposed that the Solar System began with five giant planets, a third ice giant being ejected during the instability.[^nesvorny2011][^batygin2012] In this version the five giants start in a resonant chain, 3:2, 3:2, 2:1 and 3:2, with a planetesimal disc beyond.[^nesvorny2012] After the chain breaks, Neptune first migrates outward into the disc to about 28 AU before planetary encounters begin; that migration thins the disc enough that Jupiter's eccentricity survives, and it produces a Kuiper belt inclination distribution that matches observations if about 20 Earth masses remained in the disc.[^nesvorny2012][^nesvorny2015b] Because Neptune then meets only the ice giant that is ejected, its eccentricity can stay low and a cold classical belt formed in place can survive.[^nesvorny2015a] The lighter disc also reduces the ice loss from Saturn's inner moons.[^dones2013] Open questions remain. A late break-up of the resonant chain combined with Neptune's migration to 28 AU is difficult to reconcile with the Nice 2 mechanism; a slow, dust-driven migration over several million years after an early escape from resonance may bridge the gap.[^deienno2017] A 2016 study found that the terrestrial planets rarely survive the instability intact, which suggests that it occurred before they had finished forming and so could not have caused a late bombardment.[^kaib2016] An early instability has its own cost: to preserve the asteroid belt it requires large jumps in the orbits of Jupiter and Saturn.[^walsh2011][^toliou2016] ## See also - [[Formation_and_evolution_of_the_Solar_System]] - [[Grand_tack_hypothesis]] - [[Late_Heavy_Bombardment]] - [[Planet_Nine]] - Jumping-Jupiter scenario · Planetary migration ## References [^tsiganis2005]: Tsiganis, K.; Gomes, R.; Morbidelli, A.; Levison, H. F. (2005). "Origin of the orbital architecture of the giant planets of the Solar System". *Nature* 435: 459–461. https://doi.org/10.1038/nature03539 [^morbidelli2005]: Morbidelli, A.; Levison, H. F.; Tsiganis, K.; Gomes, R. (2005). "Chaotic capture of Jupiter's Trojan asteroids in the early Solar System". *Nature* 435: 462–465. https://doi.org/10.1038/nature03540 [^gomes2005]: Gomes, R.; Levison, H. F.; Tsiganis, K.; Morbidelli, A. (2005). "Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets". *Nature* 435: 466–469. https://doi.org/10.1038/nature03676 [^levison2008]: Levison, H. F.; Morbidelli, A.; Van Laerhoven, C.; Gomes, R.; Tsiganis, K. (2008). "Origin of the structure of the Kuiper belt during a dynamical instability in the orbits of Uranus and Neptune". *Icarus* 196: 258–273. https://doi.org/10.1016/j.icarus.2007.11.035 [^levison2011]: Levison, H. F.; Morbidelli, A.; Tsiganis, K.; Nesvorný, D.; Gomes, R. (2011). "Late orbital instabilities in the outer planets induced by interaction with a self-gravitating planetesimal disk". *The Astronomical Journal* 142: 152. https://doi.org/10.1088/0004-6256/142/5/152 [^nesvorny2011]: Nesvorný, D. (2011). "Young Solar System's fifth giant planet?". *The Astrophysical Journal Letters* 742: L22. https://doi.org/10.1088/2041-8205/742/2/L22 [^jpl-t1]: JPL Solar System Dynamics. "Approximate positions of the planets", Table 1. https://ssd.jpl.nasa.gov/planets/approx_pos.html [^nasa-fs]: NASA NSSDCA. "Planetary Fact Sheet". https://nssdc.gsfc.nasa.gov/planetary/factsheet/ (fetched 2026-09-18). [^boekholt2015]: Boekholt, T.; Portegies Zwart, S. (2015). "On the reliability of N-body simulations". *Computational Astrophysics and Cosmology* 2: 2. https://doi.org/10.1186/s40668-014-0005-3 [^hansen2005]: Hansen, K. (7 June 2005). "Orbital shuffle for early solar system". *Geotimes*. http://www.geotimes.org/june05/WebExtra060705.html [^baldwin2010]: Baldwin, E. (25 January 2010). "Comet impacts explain Ganymede–Callisto dichotomy". *Astronomy Now*. https://astronomynow.com/news/n1001/25galilean/ [^nimmo2012]: Nimmo, F.; Korycansky, D. G. (2012). "Impact-driven ice loss in outer Solar System satellites: consequences for the Late Heavy Bombardment". *Icarus* 219: 508–510. https://doi.org/10.1016/j.icarus.2012.01.016 [^harrison2018]: Harrison, T. M.; Hodges, K. V. (2018). "Problematic evidence of a Late Heavy Bombardment". *The First Billion Years: Bombardment*, LPI Contribution 2107, abstract 2031. Bibcode 2018LPICo2107.2031H. [^cartwright2022]: Cartwright, J.; Hodges, K. V.; Wadhwa, M. (2022). "Evidence against a Late Heavy Bombardment event on Vesta". *Earth and Planetary Science Letters* 590: 117576. https://doi.org/10.1016/j.epsl.2022.117576 [^crida2009]: Crida, A. (2009). "Solar System formation". *Reviews in Modern Astronomy* 21: 215–227. https://doi.org/10.1002/9783527629190.ch12 [^levison2009]: Levison, H. F.; Bottke, W. F.; Gounelle, M.; et al. (2009). "Contamination of the asteroid belt by primordial trans-Neptunian objects". *Nature* 460: 364–366. https://doi.org/10.1038/nature08094 [^bottke2008]: Bottke, W. F.; Levison, H. F.; Morbidelli, A.; Tsiganis, K. (2008). "The collisional evolution of objects captured in the outer asteroid belt during the Late Heavy Bombardment". *39th Lunar and Planetary Science Conference*, abstract 1447. Bibcode 2008LPI....39.1447B. [^demeo2014]: DeMeo, F. E.; Binzel, R. P.; Carry, B.; Polishook, D.; Moskovitz, N. A. (2014). "Unexpected D-type interlopers in the inner main belt". *Icarus* 229: 392–399. https://doi.org/10.1016/j.icarus.2013.11.026 [^nesvorny2007]: Nesvorný, D.; Vokrouhlický, D.; Morbidelli, A. (2007). "Capture of irregular satellites during planetary encounters". *The Astronomical Journal* 133: 1962–1976. https://doi.org/10.1086/512850 [^nesvorny2004]: Nesvorný, D.; Beaugé, C.; Dones, L. (2004). "Collisional origin of families of irregular satellites". *The Astronomical Journal* 127: 1768–1783. https://doi.org/10.1086/382099 [^bottke2010]: Bottke, W. F.; Nesvorný, D.; Vokrouhlický, D.; Morbidelli, A. (2010). "The irregular satellites: the most collisionally evolved populations in the Solar System". *The Astronomical Journal* 139: 994–1014. https://doi.org/10.1088/0004-6256/139/3/994 [^agnor2006]: Agnor, C. B.; Hamilton, D. P. (2006). "Neptune's capture of its moon Triton in a binary–planet gravitational encounter". *Nature* 441: 192–194. https://doi.org/10.1038/nature04792 [^vokrouhlicky2008]: Vokrouhlický, D.; Nesvorný, D.; Levison, H. F. (2008). "Irregular satellite capture by exchange reactions". *The Astronomical Journal* 136: 1463–1476. https://doi.org/10.1088/0004-6256/136/4/1463 [^lovett2010]: Lovett, R. (2010). "Kuiper belt may be born of collisions". *Nature* (news). https://doi.org/10.1038/news.2010.522 [^wolff2012]: Wolff, S.; Dawson, R. I.; Murray-Clay, R. A. (2012). "Neptune on tiptoes: dynamical histories that preserve the cold classical Kuiper belt". *The Astrophysical Journal* 746: 171. https://doi.org/10.1088/0004-637X/746/2/171 [^batygin2011]: Batygin, K.; Brown, M. E.; Fraser, W. C. (2011). "Retention of a primordial cold classical Kuiper belt in an instability-driven model of Solar System formation". *The Astrophysical Journal* 738: 13. https://doi.org/10.1088/0004-637X/738/1/13 [^dones2004]: Dones, L.; Weissman, P. R.; Levison, H. F.; Duncan, M. J. (2004). "Oort cloud formation and dynamics". In *Star Formation in the Interstellar Medium*, ASP Conference Series 323, p. 371. Bibcode 2004ASPC..323..371D. [^brasser2013]: Brasser, R.; Morbidelli, A. (2013). "Oort cloud and scattered disc formation during a late dynamical instability in the Solar System". *Icarus* 225: 40–49. https://doi.org/10.1016/j.icarus.2013.03.012 [^morbidelli2007]: Morbidelli, A.; Tsiganis, K.; Crida, A.; Levison, H. F.; Gomes, R. (2007). "Dynamics of the giant planets of the Solar System in the gaseous protoplanetary disk and their relationship to the current orbital architecture". *The Astronomical Journal* 134: 1790–1798. https://doi.org/10.1086/521705 [^brasser2009]: Brasser, R.; Morbidelli, A.; Gomes, R.; Tsiganis, K.; Levison, H. F. (2009). "Constructing the secular architecture of the solar system II: the terrestrial planets". *Astronomy & Astrophysics* 507: 1053–1065. https://doi.org/10.1051/0004-6361/200912878 [^morbidelli2010]: Morbidelli, A.; Brasser, R.; Gomes, R.; Levison, H. F.; Tsiganis, K. (2010). "Evidence from the asteroid belt for a violent past evolution of Jupiter's orbit". *The Astronomical Journal* 140: 1391–1401. https://doi.org/10.1088/0004-6256/140/5/1391 [^nesvorny2014]: Nesvorný, D.; Vokrouhlický, D.; Deienno, R. (2014). "Capture of irregular satellites at Jupiter". *The Astrophysical Journal* 784: 22. https://doi.org/10.1088/0004-637X/784/1/22 [^nesvorny2013]: Nesvorný, D.; Vokrouhlický, D.; Morbidelli, A. (2013). "Capture of trojans by jumping Jupiter". *The Astrophysical Journal* 768: 45. https://doi.org/10.1088/0004-637X/768/1/45 [^bottke2012]: Bottke, W. F.; Vokrouhlický, D.; Minton, D.; et al. (2012). "An Archaean heavy bombardment from a destabilized extension of the asteroid belt". *Nature* 485: 78–81. https://doi.org/10.1038/nature10967 [^vokrouhlicky2016]: Vokrouhlický, D.; Bottke, W. F.; Nesvorný, D. (2016). "Capture of trans-Neptunian planetesimals in the main asteroid belt". *The Astronomical Journal* 152: 39. https://doi.org/10.3847/0004-6256/152/2/39 [^batygin2012]: Batygin, K.; Brown, M. E.; Betts, H. (2012). "Instability-driven dynamical evolution model of a primordially five-planet outer Solar System". *The Astrophysical Journal Letters* 744: L3. https://doi.org/10.1088/2041-8205/744/1/L3 [^nesvorny2012]: Nesvorný, D.; Morbidelli, A. (2012). "Statistical study of the early Solar System's instability with four, five, and six giant planets". *The Astronomical Journal* 144: 117. https://doi.org/10.1088/0004-6256/144/4/117 [^nesvorny2015a]: Nesvorný, D. (2015). "Jumping Neptune can explain the Kuiper belt kernel". *The Astronomical Journal* 150: 68. https://doi.org/10.1088/0004-6256/150/3/68 [^nesvorny2015b]: Nesvorný, D. (2015). "Evidence for slow migration of Neptune from the inclination distribution of Kuiper belt objects". *The Astronomical Journal* 150: 73. https://doi.org/10.1088/0004-6256/150/3/73 [^dones2013]: Dones, L.; Levison, H. F. (2013). "The impact rate on giant planet satellites during the Late Heavy Bombardment". *44th Lunar and Planetary Science Conference*, abstract 2772. http://www.lpi.usra.edu/meetings/lpsc2013/eposter/2772.pdf [^deienno2017]: Deienno, R.; Morbidelli, A.; Gomes, R. S.; Nesvorný, D. (2017). "Constraining the giant planets' initial configuration from their evolution: implications for the timing of the planetary instability". *The Astronomical Journal* 153: 153. https://doi.org/10.3847/1538-3881/aa5eaa [^kaib2016]: Kaib, N. A.; Chambers, J. E. (2016). "The fragility of the terrestrial planets during a giant-planet instability". *Monthly Notices of the Royal Astronomical Society* 455: 3561–3569. https://doi.org/10.1093/mnras/stv2554 [^walsh2011]: Walsh, K. J.; Morbidelli, A. (2011). "The effect of an early planetesimal-driven migration of the giant planets on terrestrial planet formation". *Astronomy & Astrophysics* 526: A126. https://doi.org/10.1051/0004-6361/201015277 [^toliou2016]: Toliou, A.; Morbidelli, A.; Tsiganis, K. (2016). "Magnitude and timing of the giant planet instability: a reassessment from the perspective of the asteroid belt". *Astronomy & Astrophysics* 592: A72. https://doi.org/10.1051/0004-6361/201628658 ## External links - Tsiganis, K.; Gomes, R.; Morbidelli, A.; Levison, H. F. (2005), the founding *Nature* paper. https://doi.org/10.1038/nature03539 - Southwest Research Institute, Planetary Science Directorate (Boulder). https://www.boulder.swri.edu/ - JPL Solar System Dynamics: planetary orbital elements. https://ssd.jpl.nasa.gov/planets/approx_pos.html ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Nice_model) : [Wikitube](https://en.wikitube.io/wiki/Nice_model) · pinned revision [1372335603](https://en.wikipedia.org/w/index.php?oldid=1372335603) · 2026-09-18 ## Previous hub tags Hubs: `Life_Physics`. Portals: [[PORTAL_Solar_System]]. --- *Solar System portal child articles, wave 1 · 2026-09-18 · drafted · row SOL-035 · explorer state `?view=composition`.*