Jupiter 722 000 15 Amalthea 558 000 10 Io 1 130 000 20 Europa 206 000 4 Ganymede 62 000 1 Callisto 215 000 4 [Illustration: Voyager scientists anxiously awaited the first views of Io that would show whether the volcanic eruptions seen in March were still active. This picture was taken on July 4, at a range of 4.7 million kilometers, about the same as that of the volcano discovery picture on March 8. One large plume is clearly visible, rising nearly 200 kilometers above the surface. At the time of release of this picture on July 6, the scientists wrote, “The volcano apparently has been erupting since it was observed by Voyager 1 in March. This suggests that the volcanoes on Io probably are in continuous eruption.” [P-21738B/W]] Thursday, July 5. (_Range to Jupiter, 4.4 million kilometers_). The press room at Von Karman Auditorium opened and the members of the press, most of them veterans of the first encounter, arrived at JPL. Meanwhile, the spacecraft continued to measure fluctuations in the magnetospheric boundary. By noon, JPL had reported at least eleven crossings of the bow shock as the solar wind flirted with Jupiter’s magnetosphere. Apparently the solar wind was much more variable in July than it had been in March. At times the bow shock seemed to be thicker than that experienced by Voyager 1; one Voyager 2 crossing took ten minutes, whereas the longest Voyager 1 crossing was only one minute long. Even though the processes affecting the magnetosphere seemed more complex, the magnetosphere was less compressed; when Voyager 2 actually entered the magnetosphere at a distance of 62 R_J, it was much farther from Jupiter than Voyager 1 had been at its final crossing (47 R_J). Photos obtained the day before from over 4 million kilometers showed that at least one of Io’s volcanoes was still active. A total of eight ongoing eruptions had been seen by Voyager 1, and scientists were anxious to see how many of these were still erupting four months later. VOYAGER 2 BOW SHOCK (S) AND MAGNETOPAUSE (M) CROSSINGS Boundary Day Distance (R_J) _Inbound_ S 7/02 99 (multiple) S 7/02 97 S 7/03 87 M 7/04 72 (multiple) M 7/05 71 S 7/05 69 S 7/05 67 M 7/05 62 _Outbound_