Europaís frozen, disrupted surface

Europaís frozen, disrupted surface

Fig. 9.19 . Old impact craters are not visible on Jupiterís moon Europa. They must have been erased, perhaps by fresh ice produced along cracks in the thin crust or by cold glacier-like flows. The number of impact craters found on the bright, smooth surface indicates an age of approximately 100 million years. The thin, water-ice crust has undergone extensive disruption from below (upper left). Two irregular, chaotic dark features (just below center) were most likely formed when liquid water or warm ice welled up from underneath Europaís icy shell. These dark spots, technically called macula, are named Thera and Thrace after two places in Greece where Cadmus stopped in his search for Europa. This image, approximately 675 kilometers across, was taken from the Galileo spacecraft on 20 February 1997. (Courtesy of NASA/JPL.)

Copyright 2010, Professor Kenneth R. Lang, Tufts University