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Image courtesy of NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

The Poles of Io

Io is a large moon of Jupiter. Jupiter has four large moons. Io is the closest of the four to Jupiter. Io has hundreds of volcanoes. It has more active volcanoes than any place else in our Solar System. Some of those volcanoes are near Io's poles.

A volcano named Tvashtar is near Io's North Pole. Two different spacecraft have "seen" Tvashtar erupting. The Galileo spacecraft spotted a huge lava lake in the volcano's crater. It also took pictures of an eruption of a huge lava "curtain" that was 25 km (16 miles) long and at least a kilometer (three thousand feet) high! The New Horizons spacecraft took pictures of an eruption from Tvashtar in 2007.

Another volcano, named Dazhbog, is also fairly close to Io's North Pole. The Voyager spacecraft and the Hubble Space Telescope have taken pictures of Dazhbog. Dazhbog is named after a god from Slavic mythology. Tvashtar is named after the Hindu god of blacksmiths.

Io has a very thin atmosphere. It is mostly sulfur dioxide gas from the volcanoes. Jupiter has a huge magnetic field with lots of radiation trapped in it. Some of that radiation hits Io's atmosphere. It makes gases in the atmosphere glow. That glow is called the aurora, like our Northern Lights or Southern Lights on Earth. The aurora on Io is strange. It is at Io's equator, NOT at its poles!

Last modified August 3, 2009 by Randy Russell.

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Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA