StarChild Question of the Month for May 2001


What is so important about volcanoes on Io?



The Cassini spacecraft, launched in October of 1997, is on its way to study the planet Saturn. Along the way Cassini performed a flyby of Jupiter and its moons. Cassini, along with the spacecraft Galileo that is currently in a prolonged orbit around Jupiter, observed the planet between November, 2000 and February, 2001. The two spacecraft observed the planet and its moons from different vantage points; Cassini from 10 million kilometers and Galileo from 1 million kilometers. While observing Jupiter's moon Io, the two spacecraft captured images of a volcanic plume coming from the moon's surface. The images also clearly revealed a ring of fresh deposits on the surface surrounding the volcano. If the deposits are at least 1 millimeter thick, then this newest eruption produced more ash than the 1980 eruption of Mount St. Helens in the Pacific Northwest State of Washington. The plume from the volcano is approximately 400 kilometers in height.

Image from Galileo satellite of  the pele volcano on Io.
Previously a plume was detected from an equatorial volcano named Pele (shown in the image on the left), which has been active for over 4 years. The newest volcano was detected in a region called Tvashtar Catena near Io's north pole. This is unusual since previous plumes were observed only within Io's equatorial region. Io is currently the most volcanically active body in our Solar System. Galileo will continue its observations of Jupiter and its moons while Cassini is now on its way to Saturn. It will enter into an orbit around the planet Saturn in July of 2004.



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