Abstract
The interaction of the solar wind with Earth's magnetosphere gives rise to the bright polar aurorae and to geomagnetic storms1, but the relation between the solar wind and the dynamics of the outer planets' magnetospheres is poorly understood. Jupiter's magnetospheric dynamics and aurorae are dominated by processes internal to the jovian system2, whereas Saturn's magnetosphere has generally been considered to have both internal and solar-wind-driven processes. This hypothesis, however, is tentative because of limited simultaneous solar wind and magnetospheric measurements. Here we report solar wind measurements, immediately upstream of Saturn, over a one-month period. When combined with simultaneous ultraviolet imaging3 we find that, unlike Jupiter, Saturn's aurorae respond strongly to solar wind conditions. But in contrast to Earth, the main controlling factor appears to be solar wind dynamic pressure and electric field, with the orientation of the interplanetary magnetic field playing a much more limited role. Saturn's magnetosphere is, therefore, strongly driven by the solar wind, but the solar wind conditions that drive it differ from those that drive the Earth's magnetosphere.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Dungey, J. W. Interplanetary magnetic field and the auroral zone. Phys. Rev. Lett. 6, 47–48 (1961)
Hill, T. W., Dessler, A. J. & Goertz, C. K. in Physics of the Jovian Magnetosphere (ed. Dessler, A. J.) 353–394 (Cambridge Univ. Press, Cambridge, 1983)
Clarke, J. T. et al. Morphological differences of Saturn's ultraviolet aurorae and those of Earth and Jupiter. Nature doi:10.1038/nature03331 (this issue)
Meurant, M., Gerard, J.-C., Blockx, C., Hubert, B. & Coumans, V. Propagation of electron and proton shock-induced aurora and the role of the interplanetary magnetic field and solar wind. J. Geophys. Res. 109, A10210, doi:10.1029/2004JA010453 (2004)
Cowley, S. W. H. & Bunce, E. J. Origin of the main auroral oval in Jupiter's coupled magnetosphere-ionosphere system. Planet. Space Sci. 49, 1067–1088 (2001)
Zarka, P. & Genova, F. Low frequency jovian emissions and solar wind magnetic sector structure. Nature 306, 767–768 (1983)
Desch, M. D. & Barrow, C. H. Direct evidence for solar wind control of Jupiter's hectometric wavelength radio emission. J. Geophys. Res. 89, 6819–6823 (1984)
Gurnett, D. A. et al. Control of Jupiter's radio emissions and aurorae by the solar wind. Nature 415, 985–987 (2002)
Kivelson, M. G. & Southwood, D. J. First evidence of IMF control of Jovian magnetospheric boundary locations: Cassini and Galileo magnetic field measurements compared. Planet. Space Sci. 51, 891–898 (2003)
Southwood, D. J. & Kivelson, M. G. A new perspective concerning the influence of the solar wind on the Jovian magnetosphere. J. Geophys. Res. 106, 6123–6130 (2001)
Cowley, S. W. H. & Bunce, E. J. Modulation of Jupiter's main auroral oval emissions by solar wind induced expansions and compressions of the magnetosphere. Planet. Space Sci. 51, 57–79 (2003)
Desch, M. D. Evidence for solar wind control of Saturn radio emission. J. Geophys. Res. 87, 4549–4554 (1982)
Young, D. T. et al. Cassini plasma spectrometer investigation. Space Sci. Rev. (in the press)
Kurth, W. S. et al. An Earth-like correspondence between Saturn's auroral features and radio emission. Nature doi:10.1038/nature03334 (this issue)
Hanlon, P. G. et al. On the evolution of the solar wind between 1 and 5AU at the time of the Cassini-Jupiter flyby: multi spacecraft observations of ICMEs including the formation of a merged interaction region. J. Geophys. Res. 109, A09S03, doi:10.1029/2003JA010112 (2004)
Tóth, G. General code for modeling MHD flows on parallel computers: Versatile advection code. Astrophys. Lett. Commun. 34, 245–250 (1996)
Akasofu, S.-I. The solar wind-magnetosphere energy coupling and magnetospheric disturbances. Planet. Space Sci. 28, 495–509 (1980)
Russell, C. T. & McPherron, R. L. Semiannual variation of geomagnetic activity. J. Geophys. Res. 78, 92–108 (1973)
Acknowledgements
F.J.C., B.L.B., J.T.S. and D.T.Y. were supported by NASA through a Jet Propulsion Laboratory contract with SWRI; D.G.M., K.C.H. and W.S.K. were supported through other NASA/JPL contracts; P.G.H. was supported by a PPARC-UK quota studentship; and J.C.G. and D.G. were supported by the Belgian Foundation for Scientific Research (FNRS) and the PRODEX program of the ESA. This work is based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the AURA, Inc., for NASA.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Competing interests
The authors declare that they have no competing financial interests.
Rights and permissions
About this article
Cite this article
Crary, F., Clarke, J., Dougherty, M. et al. Solar wind dynamic pressure and electric field as the main factors controlling Saturn's aurorae. Nature 433, 720–722 (2005). https://doi.org/10.1038/nature03333
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/nature03333
This article is cited by
-
A Brief Review of Ultraviolet Auroral Emissions on Giant Planets
Space Science Reviews (2015)
-
Auroral Processes at the Giant Planets: Energy Deposition, Emission Mechanisms, Morphology and Spectra
Space Science Reviews (2015)
-
Solar Wind and Internally Driven Dynamics: Influences on Magnetodiscs and Auroral Responses
Space Science Reviews (2015)
-
What characterizes planetary space weather?
The Astronomy and Astrophysics Review (2014)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.
