Exploratour - Life in the Solar System
Io is very small, so there is not much gravity. For this reason, the atmosphere of Io is constantly drifting away. If it were not for the volcanic eruptions, there would be no atmosphere at all.
Io is inside the enormously powerful magnetosphere of Jupiter. With very little atmosphere, there is little protection from the radiation of the charged particles of the magnetosphere.
With little atmosphere, there is hardly a buffer between the surface and space itself. This means that the temperature above the surface is very cold. On the other hand, with all the volcanos, the surface of Io is frequently molten, therefore the surface itself is sometimes super-hot!
All together these things add up to a very hostile environment for life as we know it.
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