Astronomy Picture of the Day -- Flyby Image of Saturn's Sponge Moon Hyperion

NASA ^ | June 03, 2015 | (see photo credit)

[SunkenCiv]

Explanation: Why does this moon look like a sponge? To better investigate, NASA and ESA sent the Saturn-orbiting robotic spacecraft Cassini zooming past Saturn's moon Hyperion, once again, earlier this week. One of the images beamed back to Earth is featured above, raw and unprocessed. Visible, as expected, are many unusually shaped craters with an unusual dark material at the bottom. Although Hyperion spans about 250 kilometers, its small gravitational tug on Cassini indicates that it is mostly empty space and so has very low surface gravity. Therefore, the odd shapes of many of Hyperion's craters are thought to result from impacts that primarily compress and eject surface material -- instead of the more typical round craters that appear after a circular shock wave that explosively redistributes surface material. Cassini is on track for another flyby of Saturn's Dione in about two weeks.

[SunkenCiv]

[Credit: NASA, JPL-Caltech, SSI]

[SunkenCiv]

The Big One is barely larger than the small one.

The Big One

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[Jack Hydrazine]

It doesn’t look like a sponge, but more like a piece of coral.

[immadashell]

It’s a beach ball designed by a bipartisan subcommittee.

[onedoug]

Fascinating.

Thanks for posting.

[Red Badger]

[BenLurkin]

Looks like the whole thing was bubbling and boiling — and then flash frozen.

[Buckeye McFrog]

Definitely spongeworthy

[Western Phil]

A soft snowball?

[SunkenCiv]

Luffa.

[Delta 21]

Its infested with exogorths! Dont land there!!