Solar system’s most volcanically active body will one day become dormant

June 18th, 2009 - 1:24 pm ICT by ANI  

London, June 18 (ANI): A new study, with an analysis of more than 100 years of observations, has suggested that the Jupiter’s moon Io, which is the solar system’s most volcanically active body, will one day become dormant.

Io, which is about the size of Earth’s moon and is Jupiter’s closest large satellite, is covered with lava flows and dozens of active volcanoes.

The heat for this activity comes from the fact that the moon travels on an elongated path around Jupiter, and therefore feels the giant planet’s gravity at different strengths along its orbit.

This varying pull causes its body to deform, producing bulges that move its surface up and down by an estimated 10 metres per orbit.

This generates heat that powers the moon’s volcanism.

But, a report in New Scientist says that it will not always be so, according to a new study led by Valery Lainey of the Paris Observatory in France.

If Io were Jupiter’s only satellite, the planet’s intense gravity would eventually pull the nearby moon into a circular orbit.

The reason it travels on an elliptical path instead is because of special gravitational interactions with its nearest large sister moons, Europa and Ganymede.

For every orbit that Ganymede makes, Europa makes two and Io four - a type of gravitational relationship called a Laplace resonance.

But, Lainey and colleagues have found that the moons are, in fact, moving out of their resonance. Europa and Ganymede are gradually drifting away from Jupiter, while Io is moving towards the planet.

The team came to these conclusions after carrying out numerical calculations of Io’s orbital motion and plugging in observations of Io, Europa and Ganymede taken between 1891 and 2007.

Though different gravitational forces act on Io, with some pulling it towards Jupiter and others pushing it away, the new study suggests the inward forces win out.

Io’s spin gradually increases at the expense of its orbital speed. When it is closest to Jupiter, gravitational pulls on Io’s near side act to make the moon spin faster.

“Io loses orbital energy, its orbital period decreases, and it moves inward towards Jupiter,” explained Gerald Schubert of the University of California, Los Angeles.

It is not clear exactly when the moons will break free from their resonance.

“If this occurs on a short timescale, say 100 million years or less, then we have been lucky to see Io in its volcanic glory, because dormancy will be the fate of Io when the resonance is broken,” said Schubert. (ANI)

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