Dark Auroral Oval on Saturn Discovered in Hubble Space Telescope Ultraviolet Images
Lotfi Ben Jaffel 1,
Véronique Leers 2, and
Bill R. Sandel 3
1 Institut d'Astrophysique de Paris, Centre National de La Recherche Scientifique, F-75014 Paris, France
2 Laboratoire de Physique Atmosphérique et Planétaire, Institut d'Astrophysique, Université de Liége, 4000 Liège, Belgium
3 Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA.
Hubble Space Telescope ultraviolet images of Saturn obtained with the Faint Object Camera near 220 nanometers reveal a dark oval encircling the north magnetic pole of the planet. The opacity has an equivalent width of 
11° in latitude and is centered around 79° N. The oval shape of the dark structure and its coincidence with the aurora detected by the Voyager Ultraviolet Spectrometer suggest that the aerosol formation is related to the auroral activity.
Submitted on February 2, 1995
Accepted on June 28, 1995
