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Volcanoes glow brightly during Io eclipse

Io in eclipse. The points of light indicate glowing lava from active volcanoes, while the faint ring is caused by auroral activity (Click image to watch video sequence)  

(CNN) -- The most volcanic body in the solar system reveals bright lava flows and glowing auroras in the first video of Jupiter's moon Io during an eclipse.

Filmed by the Cassini spacecraft during last month's flyby, the images provide evidence that the auroras originate in electrical currents connecting Io and Jupiter, NASA astronomers said.

The NASA robot ship recorded the sequence while Io passed through the shadow of Jupiter during a two-hour period. While sunlight did not reflect off the satellite during the eclipse event, two types of illumination reveal its location.

The points of light indicate glowing hot lava from active volcanoes. The brightest is that of Pele, a cauldron that seems to erupt daily, according to NASA, which released the images this week.


The faint ring around Io that concentrates near the equator is caused by diffuse emissions from auroras in its tenuous atmosphere, similar to auroras on Earth.

The equatorial glow shifts slowly clockwise through the 48 frames due to the changing orientation of Jupiter's magnetic field. The video clip "confirms that these visible auroras are caused by electrical currents that flow between Io and Jupiter," mission scientists at NASA's Jet Propulsion Laboratory said in a statement.

Cassini made its closest approach to Jupiter on December 30. The spacecraft swooped to within 10 million kilometers (6.3 million miles) of the gas giant, then used the planet's gravity to boost it along on a journey to Saturn, where it is scheduled to arrive in 2004.

The Cassini mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.

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Cassini-Huygens Mission to Saturn and Titan
European Space Agency
Italian Space Agency (in Italian)

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4:30pm ET, 4/16

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