A fresh volcanic deposit on the surface of Jupiter's moon Io may help scientists trace the evolution of the solar system's most volcanically active body.
The images, captured by the unmanned Galileo spacecraft Sept. 19, show a dark deposit 250 miles long that appears to be fine-grained debris produced when a volcano blew molten rock into dustlike particles.The deposit is "a window into Io's interior," said Alfred McEwen, a research scientist at the University of Arizona in Tucson. "We've seen lots of other changes over time. This is by far the biggest."
Earth may have had such powerhouse volcanoes long ago, which could have had effects on climate change and animal extinctions, McEwen said Wednesday.
The deposit lies at the edge of the volcanic crater Pillan Patera, named after a South American god of thunder, fire and volcanoes. At the center of the deposit are probable lava flows about 15 miles long.
During an April flyby, Galileo sent back images showing volcanic activity brewing at the site. By June, Galileo and the Hubble Space Telescope observed an active volcanic plume 75 miles high over Pillan.
Scientists were unsure what the deposit is made of.
"Most of the past changes of this scale are with bright yellowish or reddish material which is rich in sulfur and sulfur dioxide," McEwen said. "It's possible the dark stuff is another form of sulfur, but it seems far more likely we have silicates in this case."
Silicates are a type of volcanic rock found on Earth.