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Saturn's equinoctial auroras
Author(s) -
Nichols J. D.,
Badman S. V.,
Bunce E. J.,
Clarke J. T.,
Cowley S. W. H.,
Crary F. J.,
Dougherty M. K.,
Gérard J.C.,
Grodent D.,
Hansen K. C.,
Kurth W. S.,
Mitchell D. G.,
Pryor W. R.,
Stallard T. S.,
Talboys D. L.,
Wannawichian S.
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2009gl041491
Subject(s) - saturn , physics , ionosphere , magnetosphere of saturn , polar , context (archaeology) , magnetosphere , radius , astronomy , hubble space telescope , magnetic field , geology , planet , magnetopause , stars , paleontology , computer security , quantum mechanics , computer science
We present the first images of Saturn's conjugate equinoctial auroras, obtained in early 2009 using the Hubble Space Telescope. We show that the radius of the northern auroral oval is ∼1.5° smaller than the southern, indicating that Saturn's polar ionospheric magnetic field, measured for the first time in the ionosphere, is ∼17% larger in the north than the south. Despite this, the total emitted UV power is on average ∼17% larger in the north than the south, suggesting that field‐aligned currents (FACs) are responsible for the emission. Finally, we show that individual auroral features can exhibit distinct hemispheric asymmetries. These observations will provide important context for Cassini observations as Saturn moves from southern to northern summer.