NASA is now pretty confident its theory that Pluto's moon Charon split apart because of an internal ocean is right.

Last October the space agency theorised that deep canyons on Charon were the result of cryovolcanism, or cold volcanic activity to you and I.

Now the agency has explained that theory in comic book terms, as follows:

“Charon’s tectonic landscape shows that, somehow, 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.”

The explanation for the expansion is rather more sober:

“Charon’s outer layer is primarily water ice. When the moon was young this layer was warmed by the decay of radioactive elements, as well as Charon’s own internal heat of formation. Scientists say Charon could have been warm enough to cause the water ice to melt deep down, creating a subsurface ocean. But as Charon cooled over time, this ocean would have frozen and expanded (as happens when water freezes), pushing the surface outward and producing the massive chasms we see today.”

Evidence for all this theorising can apparently be found in the image below.

Charon in all its post-Hulk glory. Click here to embiggen.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

What you're gazing at is some of the deeper canyons on Charon, as shot by the New Horizons probe. The top cut-out is the canyons as they appear today. The bottom cut-out depicts “color-coded topography of the same scene” that apparently tells boffins that there was once something liquid on Charon that's since re-frozen.

One last thing: that “something” that was once liquid on Charon appears to have been water. Which makes Charon a splendid spot for a very expensive ice cube. Or a mine for water to be used as fuel for rockets or people. ®