Space: Who Knew, #9

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Enceladus

No this isn't a spanish salad. It is Saturn's 6th largest moon.

About the size of the United Kingdom, Enceladus is one of three satellites in the outer solar system where active eruptions have been observed. It is thought to contain a sub-surface ocean of liquid water and because it rotates in a synchronous orbit with Saturn (that is- the same side of the moon is always pointing towards Saturn), it is always under the effects of tidal acceleration.

This generates heat in the moon, and because it is so small, it is not perfectly round. However it is constantly under pressure to maintain its nearly spherical shape, and partly because of this tidal heating large cryovolcanoes have formed on the moon.

These volcanoes (like the ones we see on earth), are under constant pressure and instead of magma; they erupt water, ammonia, or methane. The southern polar region of Enceladus seems to be the most geologically active, and it is thought that much of the water vapor escapes the moon and has generated much of the particle cloud that makes up Saturn's widest and outermost ring (the E-Ring).

Two mechanisms fuel the particles in this ring, the first is the cryovolcanoes that spew the material space-ward. Because Enceladus' escape velocity is .24 km/second or 866 km/hour (compared to Earths escape velocity of 11.1 km/second), many of these particles are able to escape the planet. The second mechanism is meteor impacts which likely launch many of the particles in the same fashion.

Perhaps the single most defining feature of this moon are the four "tiger stripes". These ridges are nearly parallel and on average descend 500 meters into the moons interior. They are likely made of crystalline water ice.

Thanks to the Cassini mission we've been lucky to get some really amazing shots of Enceladus. Next time you enjoy a salad- think a little of this Saturnian moon! Okay- I know how dorky that sounds...

Note that the link above is from 2005, when the processes on the moon were still being puzzled over.

Who knew???