IMAGES from NASA鈥檚 Galileo spacecraft show that volcanoes on Jupiter鈥檚
moon Io spewed rocky debris over a region the size of Arizona in only about five
months.
Galileo beamed back the left image on 4 April. Later, the spacecraft revealed
a plume leaping to a height of 120 kilometres in a volcanic region called Pillan
Patera. The image on the right, taken on 19 September, shows that the eruption
left a dark grey expanse of debris 400 kilometres across.
Io鈥檚 volcanism is driven by enormous internal heat. 鈥淭he heat is sufficient
to have melted Io forty times in its lifetime,鈥� says Alfred McEwen of the
University of Tucson in Arizona, one of the Galileo imaging team. He suspects
that the debris may be made of exotic silicate rocks. 鈥淭hey may be very
different to those on Earth,鈥� he added.
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