Saturn’s Kaleidoscopic Sponge
published during a new moon.


Credit: NASA/JPL/University of Arizona/Ames/Space Science Institute

On a color map, Hyperion is a splash of rainbows. As the biggest of Saturn’s oddball moons, its pockmarked composition gives the surface a psychedelic look.

In real life, it has a reddish tinge. But on a spectrometer, reds are carbon dioxide ice, also known as dry ice, and magenta is water plus carbon dioxide. Yellows are a mix of carbon dioxide and a mystery element. It’s also suspected to have frozen methane.

Best of all, it’s an uncanny doppelgänger of an object Earth is well-acquainted with: a sponge.


Credit: NASA/JPL-Caltech/Space Science Institute

Saturn has over 60 moons, which were first glimpsed by Cassini nearly a decade ago. Some are spherical, but a handful are irregular, like blobby Prometheus or two-faced Iapetus.

Scientists believe the misfits have accompanying troubled pasts: Some are captured planets, while others are debris from collisions.


Credit: NASA/ESA/JPL/SSI/Cassini Imaging Team

Hyperion is potato-shaped and likely a result of an intense wreck. It tumbles aimlessly in its distant orbit around Saturn, which is strange, too. Its sibling moon, Titan, likely influences its path with its gravity.

The moon’s spongy look might stem from its low density, which is about half that of water. Low density also indicates it has flimsy gravity, meaning bullying impactors likely compressed the surface to forms its extensive craters instead of excavating it.

Though Hyperion’s last close-up was in 2015, Cassini still isn’t done. After mission extensions, the spacecraft will have a grand finale in 2017:, which will consist of 22 dives between Saturn and its innermost ring.