Brad Smith showed the ring pictures. “As many of you who were here last night know, we got some rather nice pictures of the ring of Jupiter. It’s as though Voyager 2 was fearful that we might be becoming just a little bit apathetic after this series of marvelous discoveries and felt that it had to dazzle us one more time before it left for Saturn. The rings appear very much brighter than we had expected them to be.” The outer ring is about 6500 kilometers wide. There is material inside the ring. There is a rather sharp outer boundary and a somewhat diffuse inner region. “And it is now our belief that the material in the ring goes all the way down to the surface of Jupiter.” There is a very narrow relatively bright outer ring and an extremely faint inner ring that goes all the way down to Jupiter’s cloud tops. Larry Soderblom summarized the satellite data: With respect to the Galilean satellites, “We’re in a relatively high state of ignorance.” The Io Volcano Watch images seemed to indicate that plume P₂ was now the highest volcano on Io, since P₁ seemed to have become quiet. Io may be the easiest Galilean satellite to try to understand, because we can actually see the geological processes that are shaping the planet. Io’s “twin,” Europa, seems to be where “our highest state of ignorance” lies. “The faint bright streaks which show some relief are evidently different from the diffuse dark bands which don’t seem to show topography, but the similarity of these forms [that both the light and dark markings are of planetary scale] suggests that they must be related.” Ed Stone speculated about the other two Galilean satellites. Ganymede and Callisto are essentially identical in size, mass, and probably composition. By examining them, we can perhaps learn what happens when bodies with very similar chemistry have different “life histories” and different surface properties (there are indications that Ganymede’s crust may not have been as rigid as Callisto’s). Going further, he added that Callisto and Mercury, the least dense and the most dense, respectively, of the terrestrial-style planets, although totally different in composition and density, seem to have similar surfaces and similar histories. What would have happened to Mercury if it had been made of ice, water, and rock as Callisto is? Would it have evolved as Callisto did? [Illustration: One of the most spectacular of the Voyager 2 images was obtained from inside the shadow of Jupiter. Looking back toward the planet and the rings with its wide-angle camera, the spacecraft took these photos on July 10 from a distance of 1.5 million kilometers. The ribbon-like nature of the rings is clearly shown. The planet is outlined by sunlight scattered from a haze layer high in the atmosphere. On each side, the arms of the ring curving back toward the spacecraft are cut off by the planet’s shadow as they approach the brightly outlined disk. [P-21774B/W]]