Letter | Published:

Discrete and broadband electron acceleration in Jupiter’s powerful aurora

Nature volume 549, pages 6669 (07 September 2017) | Download Citation


The most intense auroral emissions from Earth’s polar regions, called discrete for their sharply defined spatial configurations, are generated by a process involving coherent acceleration of electrons by slowly evolving, powerful electric fields directed along the magnetic field lines that connect Earth’s space environment to its polar regions1,2. In contrast, Earth’s less intense auroras are generally caused by wave scattering of magnetically trapped populations of hot electrons (in the case of diffuse aurora) or by the turbulent or stochastic downward acceleration of electrons along magnetic field lines by waves during transitory periods (in the case of broadband or Alfvénic aurora)3,4. Jupiter’s relatively steady main aurora has a power density that is so much larger than Earth’s that it has been taken for granted that it must be generated primarily by the discrete auroral process5,6,7. However, preliminary in situ measurements of Jupiter’s auroral regions yielded no evidence of such a process8,9,10. Here we report observations of distinct, high-energy, downward, discrete electron acceleration in Jupiter’s auroral polar regions. We also infer upward magnetic-field-aligned electric potentials of up to 400 kiloelectronvolts, an order of magnitude larger than the largest potentials observed at Earth11. Despite the magnitude of these upward electric potentials and the expectations from observations at Earth, the downward energy flux from discrete acceleration is less at Jupiter than that caused by broadband or stochastic processes, with broadband and stochastic characteristics that are substantially different from those at Earth.

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  1. 1.

    et al. FAST satellite observations of electric field structures in the auroral zone. Geophys. Res. Lett. 25, 2025–2028 (1998)

  2. 2.

    , & The Fast Auroral SnapshoT (FAST) mission. Geophys. Res. Lett. 25, 2013–2016 (1998)

  3. 3.

    et al. The turbulent Alfvénic aurora. Phys. Rev. Lett. 100, 175003 (2008)

  4. 4.

    . et al. Chapter 4: in situ measurements in the auroral plasma. Space Sci. Rev. 103, 93–208 (2002)

  5. 5.

    & Origin of the main auroral oval in Jupiter’s coupled magnetosphere–ionosphere system. Planet. Space Sci. 49, 1067–1088 (2001)

  6. 6.

    The Jovian auroral oval. J. Geophys. Res. 106, 8101–8107 (2001)

  7. 7.

    , , & Magnetosphere-ionosphere coupling at Jupiter: effect of field-aligned potentials on angular momentum transport. J. Geophys. Res. 115, A09211 (2010)

  8. 8.

    et al. Jupiter’s magnetosphere and aurorae observed by the Juno spacecraft during its first polar orbits. Science 356, 826–832 (2017)

  9. 9.

    et al. Juno observations of energetic charged particles over Jupiter’s polar regions: analysis of monodirectional and bidirectional electron beams. Geophys. Res. Lett. 44, 4410–4418 (2017)

  10. 10.

    et al. Electron beams and loss cones in the auroral regions of Jupiter. Geophys. Res. Lett. 44, (2017)

  11. 11.

    in Physics of Auroral Arc Formation (eds & ) 56–66 (AGU, 1981)

  12. 12.

    et al. Mapping the electron energy in Jupiter’s aurora: Hubble spectral observations. J. Geophys. Res. 119, 9072–9088 (2014)

  13. 13.

    et al. Characteristics of north Jovian aurora from STIS FUV spectral images. Icarus 268, 215–241 (2016)

  14. 14.

    et al. Variation of Jupiter’s aurora observed by Hisaki/EXCEED: 2. Estimation of auroral parameters and magnetospheric dynamics. J. Geophys. Res. 121, 4055–4071 (2016)

  15. 15.

    et al. The Jupiter Energetic Particle Detector Instrument (JEDI) investigation for the Juno mission. Space Sci. Rev. (2013)

  16. 16.

    et al. Morphology of the UV aurorae Jupiter during Juno’s first perijove observations. Geophys. Res. Lett. 44, 4463–4471 (2017)

  17. 17.

    et al. The Jovian Auroral Distributions Experiment (JADE) on the Juno mission to Jupiter. Space Sci. Rev. (2013)

  18. 18.

    & Principles of Plasma Physics Ch. 3 (McGraw-Hill, 1973)

  19. 19.

    et al. Jupiter’s polar auroral emissions. J. Geophys. Res. 108, 1366 (2003)

  20. 20.

    , , & Alfvénic electron acceleration in aurora occurs in global Alfvén resonosphere region. Space Sci. Rev. 122, 89–95 (2006)

  21. 21.

    et al. The Juno magnetic field investigation. Space Sci. Rev. (2017)

  22. 22.

    , , & New models of Jupiter’s magnetic field constrained by the Io flux tube footprint. J. Geophys. Res. 103, 11929–11939 (1998)

  23. 23.

    et al. The ultraviolet spectrograph on NASA’s Juno mission. Space Sci. Rev. (2014)

  24. 24.

    , , & Model of the Jovian magnetic field topology constrained by the Io auroral emissions. J. Geophys. Res. 116, A05217 (2011)

  25. 25.

    et al. Energetic ion characteristics and neutral gas interactions in Jupiter’s magnetosphere. J. Geophys. Res. 109, A09S12 (2004)

  26. 26.

    et al. Jupiter’s interior and deep atmosphere: the initial pole-to-pole passes with the Juno spacecraft. Science 356, 821–825 (2017)

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We are grateful to NASA and contributing institutions that helped to make the Juno mission possible. This work was funded by NASA’s New Frontiers Program for Juno via subcontract with the Southwest Research Institute.

Author information


  1. The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA

    • B. H. Mauk
    • , D. K. Haggerty
    • , C. Paranicas
    • , G. Clark
    • , P. Kollmann
    •  & A. M. Rymer
  2. Southwest Research Institute, San Antonio, Texas, USA

    • S. J. Bolton
    • , F. Allegrini
    • , G. R. Gladstone
    • , D. J. McComas
    •  & P. Valek
  3. Jet Propulsion Laboratory, Pasadena, California, USA

    • S. M. Levin
  4. Instituto Nazionale di Astrofisica-Instituo di Astofisica e Planetologia Spaziali, Roma, Italy

    • A. Adriani
  5. Physics and Astronomy Department, University of Texas at San Antonio, San Antonio, Texas, USA

    • F. Allegrini
  6. University of Colorado, Boulder, Colorado, USA

    • F. Bagenal
  7. Université de Liège, Technologies and Astrophysics Research Institute, Laboratoire de Physique Atmosphérique et Planétaire, Liège, Belgium

    • B. Bonfond
  8. NASA Goddard Space Flight Center, Greenbelt, Maryland, USA

    • J. E. P. Connerney
  9. University of Iowa, Iowa City, Iowa, USA

    • W. S. Kurth
  10. Princeton University, Princeton, New Jersey, USA

    • D. J. McComas


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B.H.M. is lead investigator for the Juno JEDI investigation, created Figs 1, 3 and 4 and analysed the data. D.K.H. operated the JEDI instruments during the Juno polar passes. C.P. coordinated planning of the instruments for the Juno polar passes. G.C. determined the JEDI efficiencies for quantifying the intensities of the particle fluxes. P.K. determined the out-of-band sensitivities of the JEDI instrument. A.M.R. developed the procedure for removing the minimum ionizing contamination of the electron spectra due to high-energy penetrators. S.J.B. is the principal investigator of the Juno mission. S.M.L. is a project scientist on the Juno mission. A.A. is lead investigator for the Juno Infra-Red Auroral Imager (JIRAM), helped to plan the Juno polar encounters and interpreted the auroral images. F.A. is a member of the Juno JADE plasmas sensor, helped to plan the Juno auroral encounters and interpreted the particle measurements. F.B. helped to plan the Juno polar encounters and performed the magnetic mapping of the Juno trajectory to the auroral atmosphere. B.B. is a member of the UVS imaging team and interpreted the Juno UVS auroral images. J.E.P.C. is lead investigator of the Juno magnetometer instrument and provided the magnetic field data necessary for ordering the particle data in Figs 1, 3 and 4. G.R.G. is lead investigator of the Juno UVS instrument and generated Fig. 2. W.S.K. is lead investigator of the Juno Waves investigation and helped to plan and interpret the observations of Jupiter’s polar regions. D.J.M. is the lead developer of the Juno JADE plasma instrument and helped to interpret the electron measurements. P.V. is the lead investigator for the Juno JADE instrument, and helped to plan the Juno polar encounters and interpret the electron measurements.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to B. H. Mauk.

Reviewer Information Nature thanks J. Clarke, T. Cravens and the other anonymous reviewer(s) for their contribution to the peer review of this work.

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