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The space adventure > Galileo III


Galileo observe Io and the plume from a volcano

Changes in the volcano Ra Patera between 1979 (top image from Voyager) and 1996 (bottom image from Galileo)

Credit : NASA

Since Voyager, we know the volcanic nature of Io. Volcanoes eject materials at several hundred kilometers altitude. In fact, this ejection is probably closer to geysers that volcanoes. The blue color indicates the presence of sulfur, which after condensation falls as "snow" to the surface of the satellite.

The Galileo probe has shown us that the temperature of the volcano was very high (1000°C) and that the lava should be formed of silicates.