NASA scientists have concluded that the distant dwarf planet Pluto’s moon Charon once had a subterranean ocean, which eventually froze, expanded and pushed out to the surface and fracture on a massive scale. Scientists analyzed the data collected from the image of Charon by NASA’s New Horizons spacecraft’s historical flyby of Pluto and its moon.

Images sent by the New Horizons in July 2015 showed a fractured landscape on Charon with valleys, scarps and ridges. The valleys are said to be deeper than 4 miles, according to the data from the spacecraft.

NASA’s researchers concluded with this theory: When Pluto’s moon Charon was in its early stages of formation, several million years ago, the residual heat and decay of radioactive elements left from its formation, kept the moon’s surface warmer. The water ice, if any, would have melted by the heat and became the source of water and ultimately forming a subsurface ocean.

However, when Charon’s surface heat eventually cooled down over the time, the subsurface ocean began to cool down to form ice, and naturally, the ice on the Charon’s surface started to expand. This expansion process, according to scientists, lifted the outer layers of Charon to form massive valleys, ridges and scarps, which forced the moon’s surface to “stretch and fracture on a massive scale.”

The image released by NASA focuses on a section of the Charon’s surface’s feature named as Serenity Chasma, which is a part of a large belt of chasms on the moon. The report also reveals that the belt of chasms in this moon is said to be the longest seen on any planet and moon in the solar system. The distance of this vast equatorial belt of chasms on Charon measures around 1,800 kilometers long and approximately 7.5 kilometers deep. Just for your information, our own Grand Canyon measures 446 kilometers long and 1.6 kilometers deep.

Scientists have also noted that there is a possibility that the Charon’s subsurface water-ice layer may have been at least partially liquid in its early days, and has since cooled down and frozen again. NASA explains about the released image’s characteristics is as follows:

This image was obtained by the Long-Range Reconnaissance Imager (LORRI) on New Horizons. North is up; illumination is from the top-left of the image. The image resolution is about 1,290 feet (394 meters) per pixel. The image measures 240 miles (386 kilometers) long, and 110 miles (175 kilometers) wide. It was obtained in a range of approximately 48,900 miles (78,700 kilometers) from Charon, about an hour and 40 minutes before New Horizons’ closest approach to Charon on July 14, 2015.