Extreme Ultraviolet Observations from Voyager 1 Encounter with Jupiter
A. L. BROADFOOT 1,
M. J. S. BELTON 1,
P. Z. TAKACS 1,
B. R. SANDEL 2,
D. E. SHEMANSKY 2,
J. B. HOLBERG 3,
J. M. AJELLO 4,
S. K. ATREYA 5,
T. M. DONAHUE 5,
H. W. Moos 6,
J. L. BERTAUX 7,
J. E. BLAMONT 7,
D. F. STROBEL 8,
J. C. MCCONNELL 9,
A. DALGARNO 10,
R. GOODY 10, and
M. B. MCELROY 10
1 Kitt Peak National Observatory, Tucson, Arizona 85726
2 Space Sciences Institute, University of Southern California Tucson Laboratories, Tucson, Arizona 85713
3 Planetary Science Institute, Pasadena, California 91101
4 Jet Propulsion Laboratory, Pasadena, California 91103
5 University of Michigan, Ann Arbor 48109
6 Johns Hopkins University, Baltimore, Maryland 21218
7 Service d'Aeronomie du CNRS, Paris, France
8 Naval Research Laboratory, Washington, D.C. 20375
9 York University, Ontario, Canada M3J 1P3
10 Harvard University, Cambridge, Massachusetts 02138
Observations of the optical extreme ultraviolet spectrum of the Jupiter planetary system during the Voyager 1 encounter have revealed previously undetected physical processes of significant proportions. Bright emission lines of S III, S IV, and O III indicating an electron temperature of 105 K have been identified in preliminary analyses of the Io plasma torus spectrum. Strong auroral atomic and molecular hydrogen emissions have been observed in the polar regions of Jupiter near magnetic field lines that map the torus into the atmosphere of Jupiter. The observed resonance scattering of solar hydrogen Lyman 
by the atmosphere of Jupiter and the solar occultation experiment suggest a hot thermosphere (
1000 K) wvith a large atomic hydrogen abundance. A stellar occultation by Ganymede indicates that its atmosphere is at most an exosphere.
Submitted on April 23, 1979
