Why Do Saturn’s Inner Moons Have Strange Shapes?

Posted: May 27 2018, 5:47am CDT | by , Updated: May 27 2018, 5:50am CDT , in Latest Science News


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Why do Saturn’s Inner Moons have Strange Shapes?
Credit: NASA/JPL-Caltech/Space Science Institute/University of Bern

Saturn's inner moons are created by violent collisions

Saturn is one of the four gas giants in our Solar System and the sixth planet from the Sun. It has 53 confirmed moons and they have opened up spaces within the rings. The small inner moons of Saturn are especially fascinating because of their odd shapes. Images taken by NASA’s Cassini spacecraft showed that Saturn’s inner moons Pan and Atlas look like giant ravioli and flying-saucer. The underlying reason as to why these moons have unique shapes has puzzled scientists for years. But now, for the first time, they explain how these moons were formed. As computer simulations demonstrate, the unique shapes of moos are caused by a series of mergers of several small moons.

The conditions around Saturn are exceptional. Since Saturn has 95 times more mass than Earth and the inner moons orbit very close to the planet, its gravitional force pull almost everything apart. So, Saturn’s inner moons couldn't have formed by gradual accretion of material around a single core. Their unusual shapes could be the result of merging collisions among similar sized little moonlets.

Based on the current orbit of the moons, researchers were able to recreate exactly the same shapes as imaged by Cassini. Computer simulations show that near head-on mergers lead to flattened objects with large equatorial ridges like the shapes of Atlas and Pan. With slightly more oblique impact angles, collisions cause elongated spaetzle-like shapes that closely resembled Saturn’s moon Prometheus.

"If the impact angle is bigger than ten degrees, the resulting shapes are not stable anymore," said Adrien Leleu a member of the NCCR PlanetS. “That is why Saturn's small moons look very different to comets that often have bilobed shapes.”

The small inner moons are believed to have originated from Saturn's rings. But the oblate shape of Saturn makes it hard for any object to leave the region. As a result, near head-on collisions become more frequent and the impact angle tends to get even lower in subsequent encounters. Such merging collisions take place either at the first encounter or after few hit-and-run events.

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.




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