Polar cap on Europa.

Photoelectric observations are reported of two occultations of Jupiter's satellite Europa by the satellite Io. The reductions in the intensity during these events exceeds predicted values by 80% and 55% for the nights of June 17, 1973, and June 24, 1973, respectively. It is concluded that Europa has a bright polar cap extending from the north pole to latitude 30 deg. The light curves for the Europa occultations are presented.