NASA/JHUAPL/SwRI

Pluto's moon Charon is bursting at the seams, astronomers find

Moons can get stretch marks, too.

JOSH HRALA
26 FEB 2016
 

Charon, one of Pluto's moons, is known primarily for its odd landscape full of valleys and ridges that make it look scarred or ripped open. Now, NASA researchers believe these odd formations may have been caused by an ancient subsurface ocean that froze and expanded long ago. 

According to the researchers, who started studying Charon’s weird tectonic faults when the New Horizons spacecraft captured images of it back in July, the moon expanded rapidly as its internal temperature cooled. This expansion caused its ice-covered surface to pull apart, creating a series of valleys that put the Grand Canyon to shame. 

 

Basically, when Charon was a young moon full of hopes and ambition, it had an extremely deep subsurface ocean sloshing around inside of it. When this water froze, it expanded just like ice cubes do in the freezer.

Since there was so much ice forming all at once, the moon’s surface couldn’t handle the pressure and buckled. Or, as the team puts it, "The moon expanded in its past, and - like Bruce Banner tearing his shirt as he becomes the Incredible Hulk - Charon’s surface fractured as it stretched."

In order to come up with this theory, the scientists studied high-definition pictures of Charon that were captured with New Horizon’s Long-Range Reconnaissance Imager (LORRI), which snapped the photo on 14 July 2015 from a distance of 78,700 kilometres away as it flew by. 

They focused their efforts on one of the largest valleys known as Serenity Chasma that stretches around Charon’s equator. The team notes that Serenity Chasma is actually one of the largest chasms in the entire solar system at 1,800 kilometres long and 7.5 kilometres deep.

"By comparison, the Grand Canyon is 277 miles (446 kilometres) long and just over a mile (1.6 kilometres) deep," they add

How this new research will influence the examination of other moons or exoplanets isn’t clear. But it stands to reason that the findings will aid NASA and other organisations understand how icy planets form and change over time. 

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