The Earth and Jupiter's moon Io are leaking heat into space, but for different reasons, says University of Hawaii astronomer David Jewitt. Jupiter’s moon gives
frame of reference for EarthBy Helen Altonn
haltonn@starbulletin.com
Scientists are fascinated with Io because "it's a different animal," he said. "We can learn about the general principles of solid planets by comparing Io with Earth."
Jewitt, who studies outer parts of the solar system with telescopes on Mauna Kea, and Scott Shepherd, graduate student in the UH Institute for Astronomy, are among about 250 scientists in Boulder, Colo., this week discussing Io, Europa and other Jupiter system members.
Much of the data was produced by the NASA Infrared Telescope operated by the Institute for Astronomy on Mauna Kea, Jewitt noted before going to the meetings.
He said a long-term research program has been conducted at NASA's infrared telescope since volcanoes were discovered on Io.
Scientists at the Boulder meeting are reviewing all new information about the solar system's biggest planet from ground-based telescopes and NASA spacecraft.
One of the latest puzzles is a Galileo spacecraft map of Io's nighttime surface temperatures showing it does not have the same pattern as Earth, where the tropics are hotter than the polar regions.
Reporting this finding, NASA said volcanic sites on Io show up as hot spots. Otherwise, night temperatures appear to be about the same near the equator as near the poles.
The source of the heat is the real issue, Jewitt said. "Why does Io have such a large internal heat source?
"The answer seems to be, because it is orbiting a very massive planet, Jupiter, it is tidily heated. As it goes around, the shape is deformed by the gravity of Jupiter."
He said: "The source of the heat is the same as you get when banging a nail with a hammer. Some of the energy from the hammer goes into the nail and makes it hot.
"Jupiter is the hammer, periodically squeezing Io, changing its shape and, we think, heating its interior."
Instead of tidal flexing, Earth's heat is primordial and generated by radioactive elements, Jewitt said. "Bottom line, that's why people are interested in Io. It is a radically different place."
Volcanoes on the surface of Io are a manifestation of the heating, Jewitt said, pointing out that it is probably the only place more volcanic than the Big Island. "The whole surface is covered by volcanoes, and a lot of them are active."
Another strange thing about Io, Jewitt added, is that many of the volcanoes blow out huge amounts of sulfur. Sulfur deposits can be found at Kilauea, but they are not dominant, he said.
UH Institute for Astronomy
