Photos of Jupiter Moon Show Spired, Dead Planet

The first high-resolution photos of Jupiter’s moon Callisto, taken by the Galileo spacecraft, show knobby spires of ice more than 300 feet tall surrounded by darker material that probably eroded from the spires.

Callisto, about the size of Mercury, is the most heavily cratered moon in the solar system, NASA scientists said Wednesday, indicating that it is geologically dead. There is no tectonic plate motion to obliterate craters. Further information is available at https://www.jpl.nasa.gov/images/callisto .

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Compiled by Times medical writer Thomas H. Maugh II