Ultraviolet emissions from the magnetic footprints of Io, Ganymede and Europa on Jupiter

J. T. Clarke, J. Ajello, G. Ballester, L. Ben Jaffel, J. Connerney, J. C. Gérard, G. R. Gladstone, W. Pryor, J. Trauger, J. H. Waite

Research output: Contribution to journalArticlepeer-review

195 Scopus citations


Io leaves a magnetic footprint on Jupiter's upper atmosphere that appears as a spot of ultraviolet emission that remains fixed underneath Io as Jupiter rotates. The specific physical mechanisms responsible for generating those emissions are not well understood, but in general the spot seems to arise because of an electromagnetic interaction between Jupiter's magnetic field and the plasma surrounding Io, driving currents of around 1 million amperes down through Jupiter's ionosphere. The other galilean satellites may also leave footprints, and the presence or absence of such footprints should illuminate the underlying physical mechanism by revealing the strengths of the currents linking the satellites to Jupiter. Here we report persistent, faint, far-ultraviolet emission from the jovian footprints of Ganymede and Europa. We also show that Io's magnetic footprint extends well beyond the immediate vicinity of Io's flux-tube interaction with Jupiter, and much farther than predicted theoretically; the emission persists for several hours downstream. We infer from these data that Ganymede and Europa have persistent interactions with Jupiter's magnetic field despite their thin atmospheres.

Original languageEnglish (US)
Pages (from-to)997-1000
Number of pages4
Issue number6875
StatePublished - Feb 28 2002
Externally publishedYes

ASJC Scopus subject areas

  • General


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