Thursday, June 10, 2010

The Young Moons of Saturn

New computer models suggest that five of Saturn's small moons -- Atlas, Janus, Pandora, Prometheus, and Epimetheus -- are much younger than previously thought, formed as recently as 10 million years ago.

According to Physorg:
Until now most scientists believed the tiny ring moons [...] orbiting the planet just inside or just outside the planet’s rings were formed at the beginning of the solar system some 4.5 billion years ago and were captured by Saturn’s gravity. One problem with this theory is that the tiny moonlets, some of which are under 50 kilometers across, should have been destroyed by comets over time.

If the ring moons had formed at the beginning of the solar system they ought to be similar in density to asteroids, but the data gathered by Cassini shows the density of the moons is under one gram per cubic centimeter, which is far less than asteroid rock. This suggests they did not condense from a primordial disk of dust and gas at all.

The computer models now suggest that the moons were formed by accretion of rock and ice from Saturn's ring system. And since this process is still active today, new moons may be in the cards for the future. So we've got that to look forward to.

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