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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". The curtain was 25 km (16 miles) long and at least a kilometer (three thousand feet) high! The New Horizons spacecraft also took pictures of an eruption from Tvashtar.

Another volcano, named Dazhbog, is also pretty close to Io's North Pole. The Voyager spacecraft took pictures of Dazhbog. So did the Hubble Space Telescope. 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. It is 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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