So Long, Hyperion, and Thanks for all the Pits
Saturn’s moon Hyperion looks more like a frosted honeycomb or cosmic kitchen sponge than just another cratered old sphere. In fact, the 360-kilometer long moon is one of the more bizarre-looking objects in the solar system. On May 31, NASA’s Cassini spacecraft took its last good look at the strange little world.
From 34,000 kilometers away, Cassini snapped its final closeups of oblong Hyperion. Earlier in its tour of the Saturnian system, the spacecraft had revealed for the first time the true extent of Hyperion’s weirdness, which had only been hinted at in Voyager 2 observations. Those Cassini images, shot in 2005, have since become iconic views of a moon that really is unlike anything else in the solar system.
This time around, there was a chance scientists could take a look at Hyperion’s other side.
But it was not to be. Unlike most other moons in the solar system that spin like a top around a fixed axis, Hyperion tumbles. It rotates chaotically, meaning that up, down, left, and right are more or less random, a non-pattern produced in part by gravitational interactions with Saturn’s giant moon Titan. So, as Cassini approached Hyperion over this past weekend, there was no predicting which part of the moon it would see.
Turns out, it captured the same enigmatic, familiar face from a decade ago.
Over that decade, we’ve learned that Hyperion’s unusual appearance can be blamed on its extremely low density. It’s roughly equal parts space and substance, and about half the density of water. So, rather than excavating material from the moon, impactors simply press themselves into and compress the moon’s surface, creating those odd-looking pits. And because Hyperion’s gravity is so weak, any material that’s blown off during impact just keeps flying into space instead of falling back to the surface and obscuring the craters’ original shapes.
That’s not all. Tucked into the bottoms of Hyperion’s pits are dark compounds that are likely a frigid hydrocarbon slurry. These compounds are actually vaguely reddish — which is why Hyperion appears slightly ruddy in natural-color images.
There won’t be any more close-up shots of Hyperion from Cassini. The spacecraft’s journey through the Saturn system is scheduled to end in 2017, and farflung Hyperion isn’t close enough for another flyby. But until the spacecraft plunges into Saturn, it will continue gathering data about Saturn’s wonderfully diverse and mysterious moons, and then begin diving through the space between the planet and its rings.
Related Topics
Go Further
Animals
- Octopuses have a lot of secrets. Can you guess 8 of them?
- Animals
- Feature
Octopuses have a lot of secrets. Can you guess 8 of them? - This biologist and her rescue dog help protect bears in the AndesThis biologist and her rescue dog help protect bears in the Andes
- An octopus invited this writer into her tank—and her secret worldAn octopus invited this writer into her tank—and her secret world
- Peace-loving bonobos are more aggressive than we thoughtPeace-loving bonobos are more aggressive than we thought
Environment
- Listen to 30 years of climate change transformed into haunting musicListen to 30 years of climate change transformed into haunting music
- This ancient society tried to stop El Niño—with child sacrificeThis ancient society tried to stop El Niño—with child sacrifice
- U.S. plans to clean its drinking water. What does that mean?U.S. plans to clean its drinking water. What does that mean?
- Food systems: supporting the triangle of food security, Video Story
- Paid Content
Food systems: supporting the triangle of food security - Will we ever solve the mystery of the Mima mounds?Will we ever solve the mystery of the Mima mounds?
History & Culture
- Strange clues in a Maya temple reveal a fiery political dramaStrange clues in a Maya temple reveal a fiery political drama
- How technology is revealing secrets in these ancient scrollsHow technology is revealing secrets in these ancient scrolls
- Pilgrimages aren’t just spiritual anymore. They’re a workout.Pilgrimages aren’t just spiritual anymore. They’re a workout.
- This ancient society tried to stop El Niño—with child sacrificeThis ancient society tried to stop El Niño—with child sacrifice
- This ancient cure was just revived in a lab. Does it work?This ancient cure was just revived in a lab. Does it work?
Science
- The unexpected health benefits of Ozempic and MounjaroThe unexpected health benefits of Ozempic and Mounjaro
- Do you have an inner monologue? Here’s what it reveals about you.Do you have an inner monologue? Here’s what it reveals about you.
- Jupiter’s volcanic moon Io has been erupting for billions of yearsJupiter’s volcanic moon Io has been erupting for billions of years
- This 80-foot-long sea monster was the killer whale of its timeThis 80-foot-long sea monster was the killer whale of its time
Travel
- How to plan an epic summer trip to a national parkHow to plan an epic summer trip to a national park
- This town is the Alps' first European Capital of CultureThis town is the Alps' first European Capital of Culture
- This royal city lies in the shadow of Kuala LumpurThis royal city lies in the shadow of Kuala Lumpur
- This author tells the story of crypto-trading Mongolian nomadsThis author tells the story of crypto-trading Mongolian nomads