A chasm in Charon’s southern hemisphere turns out to be longer and deeper than Earth’s Grand Canyon, says William McKinnon (Washington University, St. Louis), deputy lead scientist with New Horizon’s Geology and Geophysics investigation team.

“This is the first clear evidence of faulting and surface disruption on Charon. New Horizons has transformed our view of this distant moon from a nearly featureless ball of ice to a world displaying all kinds of geologic activity.”

Image: Chasms, craters, and a dark north polar region are revealed in this image of Pluto’s largest moon Charon taken by New Horizons on July 11, 2015. Credit: NASA/JHUAPL/SWRI.

The most prominent crater, near Charon’s south pole, is almost 100 kilometers across, and evidently the result of a geologically recent impact. This NASA news release adds that the darkness of the crater floor may be the result of a different kind of icy material being exposed, less reflective than the ices on the surface. Another possibility: The ice of the crater floor has a larger grain size, reflecting less sunlight. This would be the result of ice melting during the impact event and re-freezing into larger grains.

Image: This annotated version of the Charon imagery includes a diagram showing Charon’s north pole, equator, and central meridian, with the features highlighted. Credit: NASA/JHUAPL/SWRI.

Meanwhile, the dark region near Charon’s north pole bears watching, with more detailed images coming up on the 14th.