Here's Why Saturn's Inner Moons Are Shaped Like Ravioli and Potatoes

Space.com ^ | May 22, 2018 06:34am ET | Charles Q. Choi

[BenLurkin]

The Cassini spacecraft, which studied the ringed planet up close for 13 years, revealed that unlike Earth's spherical moon, the small moons closest to Saturn had strange, irregular shapes.

…

Previous research had suggested ways in which each of these bizarre moons might have formed. However, until now, researchers did not have an explanation that encompassed the whole range of these unusual shapes, study lead author Adrien Leleu, a dynamicist at the University of Bern in Switzerland, told Space.com.Leleu's team ran computer simulations to see how the shapes of Saturn's inner moons might have evolved over time. The powerful effects of Saturn's gravitational pull were a key influence on these simulations.

Saturn's mass is 95 times Earth's mass, and Saturn's inner moons orbit the giant planet at a distance of less than half that between Earth and its moon. As such, Saturn's inner moons experience huge tidal forces that can pull them apart, the researchers said. The planet's powerful gravitational pull made it unlikely that Saturn's inner moons formed by gradual accretion of material around a core...Instead, the researchers found that Saturn's inner moons likely formed through a series of collisions between tiny moonlets, known as the pyramidal regime formation scenario.

The strange small moons of Saturn, as imaged by the Cassini spacecraft (top), compared to moons created through simulated collisions. Not only are they similar shapes, but the model suggests why Pan's and Atlas' ridges look different: The ridges are made from smooth material squeezed out from the middle during the merger.

Credit: NASA/JPL-Caltech/Space Science Institute/University of Bern

[marron]

Maybe they are relatively new?

[Red Badger]

Gravity.....................

[Red Badger]

New Moon!

You saw me standing alone!

Without a dream in my heart,

Without a love of my own....................

[SunkenCiv]

Thanks BenLurkin. Obviously Saturn is another secret Vatican project!!! /sarc

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[gr8eman]

Why am I suddenly craving donuts?

[Doctor DNA]

Too much man made solar warming melted them?

[Paal Gulli]

Astrofizzicists theorize that a planet has to be of a certain minimum size (diameter) before it's own internal gravitational forces will be strong enough to pull it into a spherical shape. Planets smaller than that minimum size tend to remain "potato-shaped," so they have termed this factor the potato radius.

The 'rule of thumb' for potato radius is 200km, and the three moons in consideration, Pan, Atlas and Prometheus, all are well less than 100km in diameter. Plus they orbit much closer to a massively larger planet, so their own internal gravity has to contend with Saturn's overwhelming tidal forces.

Earth's moon suffered a massive collision and still managed to pull itself into a spherical shape but it is more than 7x larger than the potato radius, and orbits well further from a much smaller planet. So it stands to reason that such small moons orbiting so close to such a large planet would eternally show the aftereffects of ancient collisions.

[Libloather]

Is this where the octopuses came from?

https://nypost.com/2018/05/18/scientists-suggest-octopuses-might-actually-be-aliens/amp/

[sit-rep]

((((((( Ggoonngg!! )))))))

Get out the hook!

[BenLurkin]

[blueunicorn6]

I knew it.

I just knew it.

[Silentgypsy]

I know what you mean. Everything reminds me of food, too.

[Silentgypsy]

What a fun concept!