Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Formation of Mercury by a grazing giant collision involving similar-mass bodies

Nature Astronomy volume 9, pages 1158–1166 (2025)Cite this article

Subjects

Abstract

The origin of Mercury still remains poorly understood compared with the other rocky planets of the Solar System. To explain its internal structure, it is usually considered to be the product of a giant impact. However, most studies assume a binary collision between bodies of substantially different masses, which seems to be unlikely according to N-body simulations. Here, we perform smoothed-particle hydrodynamics simulations to investigate the conditions under which collisions of similar-mass bodies are able to form a Mercury-like planet. Our results show that such collisions can fulfil the necessary constraints in terms of mass (0.055 M⊕) and composition (30/70 silicate-to-iron mass ratio) within less than 5%, as long as the impact angles and velocities are properly adjusted according to well established scaling laws. With these results, we broaden the scope of plausible formation scenarios by presenting those that are more frequent in numerical simulations, less constrained in planetary contexts and thus more likely to happen.

Access through your institution
Buy or subscribe

This is a preview of subscription content, access via your institution

Access options

Access through your institution

Buy this article

  • Purchase on SpringerLink
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Distribution of hit-and-run collisions detected in N-body simulations of terrestrial planet accretion in the Solar System, in terms of different parameters.
Fig. 2: Relationship between the different impact parameters for the simulations in the group A configuration.
Fig. 3: Summary of the outcomes of our SPH simulations for the group A configurations (target core-mass ratio of 0.5).
Fig. 4: Snapshots of the collision in the BF configuration with a target of 0.2 M⊕.
Fig. 5: Comparison of the resulting Mercury candidates using different SPH resolutions in our best simulations.

Similar content being viewed by others

Data availability

The datasets generated and/or analysed during the current study are available at https://doi.org/10.5281/zenodo.15145979 (ref. 65). Additional data are available upon request from the corresponding authors. Source data are provided with this paper.

Code availability

The SPH code miluphcuda is in active development and publicly available via GitHub at https://github.com/christophmschaefer/miluphcuda.

References

  1. Peplowski, P. N. et al. Radioactive elements on Mercury’s surface from MESSENGER: implications for the planet’s formation and evolution. Science 333, 1850–1852 (2011).

    Article  Google Scholar 

  2. Nittler, L. R. et al. The major-element composition of Mercury’s surface from MESSENGER X-ray spectrometry. Science 333, 1847–1850 (2011).

    Article  Google Scholar 

  3. Evans, L. G. et al. Chlorine on the surface of Mercury: MESSENGER gamma-ray measurements and implications for the planet’s formation and evolution. Icarus 257, 417–427 (2015).

    Article  Google Scholar 

  4. Benz, W., Slattery, W. L. & Cameron, A. G. W. Collisional stripping of Mercury’s mantle. Icarus 74, 516–528 (1988).

    Article  Google Scholar 

  5. Agnor, C. & Asphaug, E. Accretion efficiency during planetary collisions. Astrophys. J. Lett. 613, L157–L160 (2004).

    Article  Google Scholar 

  6. Benz, W., Anic, A., Horner, J. & Whitby, J. A. The origin of Mercury. Space Sci. Rev. 132, 189–202 (2007).

    Article  Google Scholar 

  7. Asphaug, E. Impact origin of the Moon? Annu. Rev. Earth Planet. Sci. 42, 551–578 (2014).

    Article  Google Scholar 

  8. Ebel, D. S. & Stewart, S. T. in Mercury. The View after MESSENGER Vol. 45 (eds Solomon, S. C. et al.) 497–515 (Cambridge Univ. Press, 2018).

  9. Raymond, S. N., Izidoro, A. & Morbidelli, A. in Planetary Astrobiology (eds Meadows, V. S. et al.) 287–324 (Univ. Arizona Press, 2020).

  10. Raymond, S. N., O’Brien, D. P., Morbidelli, A. & Kaib, N. A. Building the terrestrial planets: constrained accretion in the inner Solar System. Icarus 203, 644–662 (2009).

    Article  Google Scholar 

  11. Izidoro, A., Raymond, S. N., Morbidelli, A. & Winter, O. C. Terrestrial planet formation constrained by Mars and the structure of the asteroid belt. Mon. Not. R. Astron. Soc. 453, 3619–3634 (2015).

    Article  Google Scholar 

  12. Lykawka, P. S. & Ito, T. Terrestrial planet formation: constraining the formation of Mercury. Astrophys. J. 838, 106 (2017).

    Article  Google Scholar 

  13. Izidoro, A. & Raymond, S. N. in Handbook of Exoplanets (eds Deeg, H. J. & Belmonte, J. A.) 2365–2423 (Springer, 2018).

  14. Clement, M. S., Kaib, N. A. & Chambers, J. E. Dynamical constraints on Mercury’s collisional origin. Astron. J. 157, 208 (2019).

    Article  Google Scholar 

  15. Franco, P., Izidoro, A., Winter, O. C., Torres, K. S. & Amarante, A. Explaining Mercury via a single giant impact is highly unlikely. Mon. Not. R. Astron. Soc. 515, 5576–5586 (2022).

    Article  Google Scholar 

  16. Clement, M. S., Chambers, J. E., Kaib, N. A., Raymond, S. N. & Jackson, A. P. Mercury’s formation within the early instability scenario. Icarus 394, 115445 (2023).

    Article  Google Scholar 

  17. Duncan, M. J., Levison, H. F. & Lee, M. H. A multiple time step symplectic algorithm for integrating close encounters. Astron. J. 116, 2067–2077 (1998).

    Article  Google Scholar 

  18. Chambers, J. E. A hybrid symplectic integrator that permits close encounters between massive bodies. Mon. Not. R. Astron. Soc. 304, 793–799 (1999).

    Article  Google Scholar 

  19. Chambers, J. E. Late-stage planetary accretion including hit-and-run collisions and fragmentation. Icarus 224, 43–56 (2013).

    Article  Google Scholar 

  20. Emsenhuber, A. et al. Realistic on-the-fly outcomes of planetary collisions. II. Bringing machine learning to N-body simulations. Astrophys. J. 891, 6 (2020).

    Article  Google Scholar 

  21. Burger, C., Bazsó, Á. & Schäfer, C. M. Realistic collisional water transport during terrestrial planet formation. Self-consistent modeling by an N-body–SPH hybrid code. Astron. Astrophys. 634, A76 (2020).

    Article  Google Scholar 

  22. Cameron, A. G. W., Benz, W., Fegley, B. Jr & Slattery, W. L. in Mercury (eds Vilas, F. et al.) 692–708 (Univ. Arizona Press, 1988).

  23. Asphaug, E. Similar-sized collisions and the diversity of planets. Geochemistry 70, 199–219 (2010).

    Article  Google Scholar 

  24. Asphaug, E. & Reufer, A. Mercury and other iron-rich planetary bodies as relics of inefficient accretion. Nat. Geosci. 7, 564–568 (2014).

    Article  Google Scholar 

  25. Sarid, G., Stewart, S. T. & Leinhardt, Z. M. in 45th Annual Lunar and Planetary Science Conference 2723 (LPI, 2014).

  26. Chau, A., Reinhardt, C., Helled, R. & Stadel, J. Forming Mercury by giant impacts. Astrophys. J. 865, 35 (2018).

    Article  Google Scholar 

  27. Gladman, B. & Coffey, J. Mercurian impact ejecta: meteorites and mantle. Meteorit. Planet. Sci. 44, 285–291 (2009).

    Article  Google Scholar 

  28. O’Brien, D. P., Morbidelli, A. & Levison, H. F. Terrestrial planet formation with strong dynamical friction. Icarus 184, 39–58 (2006).

    Article  Google Scholar 

  29. Jackson, A. P., Gabriel, T. S. J. & Asphaug, E. I. Constraints on the pre-impact orbits of Solar System giant impactors. Mon. Not. R. Astron. Soc. 474, 2924–2936 (2018).

    Article  Google Scholar 

  30. Stewart, S. T. et al. Mercury impact origin hypothesis survives the volatile crisis: implications for terrestrial planet formation. In 47th Annual Lunar and Planetary Science Conference https://www.hou.usra.edu/meetings/lpsc2016/pdf/2954.pdf (LPI, 2016).

  31. Clement, M. S., Kaib, N. A., Raymond, S. N., Chambers, J. E. & Walsh, K. J. The early instability scenario: terrestrial planet formation during the giant planet instability, and the effect of collisional fragmentation. Icarus 321, 778–790 (2019).

    Article  Google Scholar 

  32. Ebel, D. S. & Alexander, C. M. O. Equilibrium condensation from chondritic porous IDP enriched vapor: implications for Mercury and enstatite chondrite origins. Planet. Space Sci. 59, 1888–1894 (2011).

    Article  Google Scholar 

  33. Wurm, G., Trieloff, M. & Rauer, H. Photophoretic separation of metals and silicates: the formation of Mercury-like planets and metal depletion in chondrites. Astrophys. J. 769, 78 (2013).

    Article  Google Scholar 

  34. Pignatale, F. C., Liffman, K., Maddison, S. T. & Brooks, G. 2D condensation model for the inner Solar Nebula: an enstatite-rich environment. Mon. Not. R. Astron. Soc. 457, 1359–1370 (2016).

    Article  Google Scholar 

  35. Kruss, M. & Wurm, G. Seeding the formation of Mercurys: an iron-sensitive bouncing barrier in disk magnetic fields. Astrophys. J. 869, 45 (2018).

    Article  Google Scholar 

  36. Kruss, M. & Wurm, G. Composition and size dependent sorting in preplanetary growth: seeding the formation of Mercury-like planets. Planet. Sci. J. 1, 23 (2020).

    Article  Google Scholar 

  37. Stewart, S. T. & Leinhardt, Z. M. Collisions between gravity-dominated bodies. II. The diversity of impact outcomes during the end stage of planet formation. Astrophys. J. 751, 32 (2012).

    Article  Google Scholar 

  38. Clement, M. S., Chambers, J. E. & Jackson, A. P. Dynamical avenues for Mercury’s origin. I. The lone survivor of a primordial generation of short-period protoplanets. Astron. J. 161, 240 (2021).

    Article  Google Scholar 

  39. Gabriel, T. S. J. et al. Gravity-dominated collisions: a model for the largest remnant masses with treatment for “hit and run” and density stratification. Astrophys. J. 892, 40 (2020).

    Article  Google Scholar 

  40. Leinhardt, Z. M. & Stewart, S. T. Collisions between gravity-dominated bodies. I. Outcome regimes and scaling laws. Astrophys. J. 745, 79 (2012).

    Article  Google Scholar 

  41. Svetsov, V. Cratering erosion of planetary embryos. Icarus 214, 316–326 (2011).

    Article  Google Scholar 

  42. Cambioni, S. et al. The effect of inefficient accretion on planetary differentiation. Planet. Sci. J. 2, 93 (2021).

    Article  Google Scholar 

  43. Hubbard, A. Explaining Mercury’s density through magnetic erosion. Icarus 241, 329–335 (2014).

    Article  Google Scholar 

  44. Morbidelli, A., Lunine, J. I., O’Brien, D. P., Raymond, S. N. & Walsh, K. J. Building terrestrial planets. Annu. Rev. Earth Planet. Sci. 40, 251–275 (2012).

    Article  Google Scholar 

  45. Lawrence, D. J. et al. Evidence for water ice near Mercury’s north pole from MESSENGER neutron spectrometer measurements. Science 339, 292 (2013).

    Article  Google Scholar 

  46. Brasser, R., Mojzsis, S. J., Werner, S. C., Matsumura, S. & Ida, S. Late veneer and late accretion to the terrestrial planets. Earth Planet. Sci. Lett. 455, 85–93 (2016).

    Article  Google Scholar 

  47. Hyodo, R., Genda, H. & Brasser, R. Modification of the composition and density of Mercury from late accretion. Icarus 354, 114064 (2021).

    Article  Google Scholar 

  48. Frantseva, K. et al. Exogenous delivery of water to Mercury. Icarus 383, 114980 (2022).

    Article  Google Scholar 

  49. Schäfer, C. et al. A smooth particle hydrodynamics code to model collisions between solid, self-gravitating objects. Astron. Astrophys. 590, A19 (2016).

    Article  Google Scholar 

  50. Schäfer, C. M. et al. A versatile smoothed particle hydrodynamics code for graphic cards. Astron. Comput. 33, 100410 (2020).

    Article  Google Scholar 

  51. Thompson, S. L. ANEOS: Analytic Equations of State for Shock Physics Codes Input Manual Technical Report SAND-89-2951 (Sandia National Labs, 1990).

  52. Melosh, H. J. A hydrocode equation of state for SiO2. Meteorit. Planet. Sci. 42, 2079–2098 (2007).

    Article  Google Scholar 

  53. Grady, D. & Kipp, M. Continuum modelling of explosive fracture in oil shale. Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 17, 147–157 (1980).

    Article  Google Scholar 

  54. Benz, W. & Asphaug, E. Simulations of brittle solids using smooth particle hydrodynamics. Comput. Phys. Commun. 87, 253–265 (1995).

    Article  Google Scholar 

  55. Melosh, H. J. Impact Cratering: A Geologic Process (Oxford Univ. Press, 1989).

  56. Jutzi, M. SPH calculations of asteroid disruptions: the role of pressure dependent failure models. Planet. Space Sci. 107, 3–9 (2015).

    Article  Google Scholar 

  57. Burger, C. & Schäfer, C. M. Applicability and limits of simple hydrodynamic scaling for collisions of water-rich bodies in different mass regimes. In Proc. First Greek–Austrian Workshop on Extrasolar Planetary Systems (eds Maindl, T. I. et al.) 63–81 (2017).

  58. Emsenhuber, A., Jutzi, M. & Benz, W. SPH calculations of Mars-scale collisions: the role of the equation of state, material rheologies, and numerical effects. Icarus 301, 247–257 (2018).

    Article  Google Scholar 

  59. Diehl, S., Rockefeller, G., Fryer, C. L., Riethmiller, D. & Statler, T. S. Generating optimal initial conditions for smoothed particle hydrodynamics simulations. Publ. Astron. Soc. Aust. 32, e048 (2015).

    Article  Google Scholar 

  60. Burger, C., Maindl, T. I. & Schäfer, C. M. Transfer, loss and physical processing of water in hit-and-run collisions of planetary embryos. Cel. Mech. Dyn. Astron. 130, 2 (2018).

    Article  Google Scholar 

  61. Quintana, E. V., Barclay, T., Borucki, W. J., Rowe, J. F. & Chambers, J. E. The frequency of giant impacts on Earth-like worlds. Astrophys. J. 821, 126 (2016).

    Article  Google Scholar 

  62. Stadel, J. G. Cosmological N-Body Simulations and Their Analysis. PhD thesis, Univ. Washington (2001).

  63. Benincasa, S. M., Wadsley, J. W., Couchman, H. M. P., Pettitt, A. R. & Tasker, E. J. A tale of two clump masses: a new way to study clump formation in simulations. Mon. Not. R. Astron. Soc. 486, 5022–5036 (2019).

    Google Scholar 

  64. Timpe, M. L., Han Veiga, M., Knabenhans, M., Stadel, J. & Marelli, S. Machine learning applied to simulations of collisions between rotating, differentiated planets. Comput. Astrophys. Cosmol. 7, 2 (2020).

    Article  Google Scholar 

  65. Franco, P. et al. SPH Simulation data of article Forming Mercury by a grazing giant collision involving similar mass bodies. Zenodo https://doi.org/10.5281/zenodo.15145979 (2025).

Download references

Acknowledgements

P.F., F.R. and O.C.W. acknowledge support from the Brazilian National Council of Research—CNPq (grants 305210/2018-1 and 312429/2023-1). R.S., C.B. and C.M.S. appreciate support from the German Research Foundation—DFG (projects 285676328 and 446102036). Simulations have been performed using the cluster of the Grupo de Dinâmica Orbital e Planetologia of UNESP, financed by the São Paulo State Research Foundation—FAPESP (grant 2016/24561-0). We also thank the Brazilian Federal Agency for Support and Evaluation of Graduate Education—CAPES, in the scope of the programme CAPES-PrInt, process 88887.310463/2018-00, International Cooperation Project number 3266.

Author information

Authors and Affiliations

  1. Coordenação de Astronomia e Astrofísica, Observatório Nacional, Rio de Janeiro, Brazil

    Patrick Franco & Fernando Roig

  2. Institut de Physique du Globe de Paris, Université Paris Cité, CNRS, Paris, France

    Patrick Franco

  3. Grupo de Dinâmica Orbital e Planetologia, São Paulo State University, Guaratinguetá, Brazil

    Othon C. Winter & Rafael Sfair

  4. LIRA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CY Cergy Paris Université, CNRS, Meudon, France

    Rafael Sfair

  5. Institute of Astronomy and Astrophysics, University of Tübingen, Tübingen, Germany

    Rafael Sfair, Christoph Burger & Christoph M. Schäfer

Authors
  1. Patrick Franco
    View author publications

    Search author on:PubMed Google Scholar

  2. Fernando Roig
    View author publications

    Search author on:PubMed Google Scholar

  3. Othon C. Winter
    View author publications

    Search author on:PubMed Google Scholar

  4. Rafael Sfair
    View author publications

    Search author on:PubMed Google Scholar

  5. Christoph Burger
    View author publications

    Search author on:PubMed Google Scholar

  6. Christoph M. Schäfer
    View author publications

    Search author on:PubMed Google Scholar

Contributions

P.F. set up, performed and analysed the simulations, interpreted the results and wrote the manuscript. F.R. and O.C.W. proposed the study, advised on its execution and revised the results and the manuscript. R.S., C.B. and C.M.S. contributed with the configuration, modification and application of the SPH code. All the authors contributed to the discussion of the results.

Corresponding authors

Correspondence to Patrick Franco or Fernando Roig.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Astronomy thanks Matt Clement, Ryuki Hyodo, Nathan Kaib and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Scheme of a generic collision between two planet-sized bodies.

Schematic of a collision configuration. \(\overrightarrow{{V}_{i}}\) denotes the relative impact velocity between the target of radius Rt and the projectile of radius Rp. The impact angle, θ, is defined as the angle between the lines Rt + Rp and the relative velocity vector at the moment of first contact. Lint represents the interacting length, defined as the projected length of the projectile that overlaps the target.

Supplementary information

Supplementary Video 1

SPH simulation of the collision of a proto-Mercury, of 0.13 M⊕, with a target of 0.2 M⊕. The proto-Mercury is represented by a pink mantle and a turquoise core. The target is represented by a red mantle and a yellow core. The impact angle is 32.5°, and the impact velocity is 22.3 km s−1. The total time span of the simulation is 48 h. The resulting Mercury-like body has a ZFe of 0.68 and a mass of 0.056 M⊕, very close to the current values.

Source data

Source Data Fig. 1

Statistical source data.

Source Data Fig. 2

Statistical source data.

Source Data Fig. 3

Statistical source data.

Source Data Fig. 4

Statistical source data.

Source Data Fig. 5

Statistical source data.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Franco, P., Roig, F., Winter, O.C. et al. Formation of Mercury by a grazing giant collision involving similar-mass bodies. Nat Astron 9, 1158–1166 (2025). https://doi.org/10.1038/s41550-025-02582-y

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue date:

  • DOI: https://doi.org/10.1038/s41550-025-02582-y

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing