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Origin of the Ganymede–Callisto dichotomy by impacts during the late heavy bombardment


Jupiter’s large moons Ganymede1,2 and Callisto2,3 are similar in size and composition. However, Ganymede has a tectonically evolved surface1 and a large rock/metal core2, whereas Callisto’s surface shows no sign of resurfacing3 and the separation of ice and rock in its interior seems incomplete2. These differences have been difficult to explain4,5,6,7,8,9,10,11. Here we present geophysical models of impact-induced core formation to show that the Ganymede–Callisto dichotomy can be explained through differences in the energy received during a brief period of frequent planetary impacts about 700 million years after planet formation, termed the late heavy bombardment12,13,14,15. We propose that during the late heavy bombardment, impacts would have been sufficiently energetic on Ganymede to lead to a complete separation of rock and ice, but not on Callisto. In our model, a dichotomy between Ganymede and Callisto that is consistent with observations is created if the planetesimal disk that supplied the cometary impactors during the late heavy bombardment is about 5–30 times the mass of the Earth. Our findings are consistent with estimates of a disk about 20 times the mass of the Earth as used in dynamical models that recreate the present-day architecture of the outer solar system and the lunar late heavy bombardment15,16.

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Figure 1: Interior structures of Ganymede and Callisto after the LHB.
Figure 2: Results of Monte Carlo modelling constraining the probability of forming the Ganymede–Callisto dichotomy as a function of LHB mass.


  1. 1

    Pappalardo, R. T. et al. Jupiter: The Planet, Satellites & Magnetosphere 363–396 (Cambridge Univ. Press, 2004).

    Google Scholar 

  2. 2

    Schubert, G., Anderson, J. D., Spohn, T. & McKinnon, W. B. Jupiter: The Planet, Satellites & Magnetosphere 281–306 (Cambridge Univ. Press, 2004).

    Google Scholar 

  3. 3

    Moore, J. M. et al. Jupiter: The Planet, Satellites & Magnetosphere 397–426 (Cambridge Univ. Press, 2004).

    Google Scholar 

  4. 4

    Schubert, G., Stevenson, D. J. & Ellsworth, K. Internal structures of the Galilean satellites. Icarus 47, 46–59 (1981).

    Article  Google Scholar 

  5. 5

    Lunine, J. I. & Stevenson, D. J. Formation of the Galilean satellites in a gaseous nebula. Icarus 52, 14–39 (1982).

    Article  Google Scholar 

  6. 6

    Friedson, A. J. & Stevenson, D. J. Viscosity of rock–ice mixtures and applications to the evolution of icy satellites. Icarus 56, 1–14 (1983).

    Article  Google Scholar 

  7. 7

    Stevenson, D. J., Harris, A. W. & Lunine, J. L. Satellites 39–88 (Univ. Arizona Press, 1986).

    Google Scholar 

  8. 8

    Tittemore, W. C. Chaotic motion of Europa and Ganymede and the Ganymede–Callisto dichotomy. Science 250, 263–267 (1990).

    Article  Google Scholar 

  9. 9

    Peale, S. J. Origin and evolution of the natural satellites. Ann. Rev. Astron. Astrophys. 37, 533–602 (1999).

    Article  Google Scholar 

  10. 10

    Canup, R. M. & Ward, W. R. Formation of the Galilean satellites: Conditions of accretion. Astron. J. 124, 3404–3423 (2002).

    Article  Google Scholar 

  11. 11

    Barr, A. C. & Canup, R. M. Constraints on gas giant satellite formation from the interior states of partially differentiated satellites. Icarus 198, 163–177 (2008).

    Article  Google Scholar 

  12. 12

    Kring, D. A. & Cohen, B. A. Cataclysmic bombardment throughout the inner solar system 3.9–4.0 Ga. J. Geophys. Res. 107, 5009 (2002).

    Article  Google Scholar 

  13. 13

    Strom, R. G., Malhotra, R., Ito, T., Yoshida, F. & Kring, D. A. The origin of planetary impactors in the inner solar system. Science 309, 1847–1850 (2005).

    Article  Google Scholar 

  14. 14

    Levison, H. F. et al. Could the lunar ‘Late Heavy Bombardment’ have been triggered by the formation of Uranus and Neptune? Icarus 151, 286–306 (2001).

    Article  Google Scholar 

  15. 15

    Gomes, R., Levison, H. F., Tsiganis, K. & Morbidelli, A. Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets. Nature 435, 466–469 (2005).

    Article  Google Scholar 

  16. 16

    Tsiganis, K., Gomes, R., Morbidelli, A. & Levison, H. F. Origin of the orbital architecture of the giant planets of the Solar System. Nature 435, 459–461 (2005).

    Article  Google Scholar 

  17. 17

    Anderson, J. D. et al. Shape, mean radius, gravity field, and interior structure of Callisto. Icarus 153, 157–161 (2001).

    Article  Google Scholar 

  18. 18

    Showman, A. P. & Malhotra, R. Tidal evolution into the Laplace resonance and the resurfacing of Ganymede. Icarus 127, 93–111 (1997).

    Article  Google Scholar 

  19. 19

    Zahnle, K., Schenk, P. M. & Levison, H. F. Cratering rates in the outer solar system. Icarus 163, 263–289 (2003).

    Article  Google Scholar 

  20. 20

    McKinnon, W. B. NOTE: Mystery of Callisto: Is it undifferentiated? Icarus 130, 540–543 (1997).

    Article  Google Scholar 

  21. 21

    Petrenko, V. F. & Whitworth, R. W. Physics of Ice (Oxford Univ. Press, 1999).

    Google Scholar 

  22. 22

    Pierazzo, E., Vickery, A. M. & Melosh, H. J. A reevaluation of impact melt production. Icarus 127, 408–423 (1997).

    Article  Google Scholar 

  23. 23

    Tonks, W. B. & Melosh, H. J. Core formation by giant impacts. Icarus 100, 326–346 (1992).

    Article  Google Scholar 

  24. 24

    Tonks, W. B. & Melosh, H. J. Magma ocean formation due to giant impacts. J. Geophys. Res. 98, 5319–5333 (1993).

    Article  Google Scholar 

  25. 25

    Reese, C. C. & Solomatov, V. S. Fluid dynamics of local martian magma oceans. Icarus 184, 102–120 (2006).

    Article  Google Scholar 

  26. 26

    Peale, S. J. & Lee, M. H. A primordial origin of the Laplace relation among the Galilean satellites. Science 298, 593–597 (2002).

    Article  Google Scholar 

  27. 27

    Canup, R. M. & Ward, W. R. A common mass scaling for satellite systems of gaseous planets. Nature 441, 834–839 (2006).

    Article  Google Scholar 

  28. 28

    Morbidelli, A., Levison, H. F., Tsiganis, K. & Gomes, R. Chaotic capture of Jupiter’s Trojan asteroids in the early Solar System. Nature 435, 462–465 (2005).

    Article  Google Scholar 

  29. 29

    Mueller, S. & McKinnon, W. B. Three-layered models of Ganymede and Callisto—Compositions, structures and aspects of evolution. Icarus 76, 437–464 (1988).

    Article  Google Scholar 

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A.C.B. and R.M.C. are grateful to NASA’s Planetary Geology and Geophysics programme. We thank H. Levison, D. Nesvorný, O. Barnouin-Jha and E. Pierazzo for useful discussions, V. Mlinar and R. Citron for comments on draft manuscripts and W. B. Tonks for helpful comments.

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A.C.B. and R.M.C. formulated the model; A.C.B. carried out the calculations, and A.C.B. and R.M.C. jointly interpreted the results.

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Correspondence to Amy C. Barr.

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The authors declare no competing financial interests.

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Barr, A., Canup, R. Origin of the Ganymede–Callisto dichotomy by impacts during the late heavy bombardment. Nature Geosci 3, 164–167 (2010).

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