New Horizons sent another batch of images it took during its last Pluto flyby, and this time, the HD images are of the dwarf planet's largest moon, Charon.

"Many New Horizons scientists expected Charon to be a monotonous, crater-battered world; instead, they're finding a landscape covered with mountains, canyons, landslides, surface-color variations and more," NASA said in a statement.

The images were taken during a Pluto flyby on July 14 and reached Earth Sept. 21. The images show fractures and canyons that are four times as long and twice as deep as the Grand Canyon, indicating that Charon had a violent past.

"It looks like the entire crust of Charon has been split open," said John Spencer, deputy lead for New Horizons Geology, Geophysics and Imaging at the Southwest Research Institute in Boulder, Colo., according to Fox News.

There are also areas on the moon that showed smoother plain areas, and this is puzzling researchers. "The team is discussing the possibility that an internal water ocean could have frozen long ago, and the resulting volume change could have led to Charon cracking open, allowing water-based lavas to reach the surface at that time," said New Horizons team member Paul Schenk, according to CNET on Yahoo! News.

"We thought the probability of seeing such interesting features on this satellite of a world at the far edge of our solar system was low. [We] couldn't be more delighted with what we see," said Ross Beyer, an affiliate of the New Horizons Geology, Geophysics and Imaging team, ABC News reports.