Aside from the remarkable clarity of the images, astronomers were astounded by the topography the pictures described. On Pluto, a huge ice mountain range measures 11,000 feet high and tens of miles wide. Meanwhile, canyons on Charon look to be 3 to 6 miles deep and are part of a cluster of troughs and cliffs that stretch 600 miles.
But the thing that astounded astronomers the most was the lack of a single impact crater. This suggests a geologically active planet. Despite its icy surface, internal heat is still shaping Pluto, heat that may be coming from the decay of radioactive material normally found in planetary bodies, or from energy released by the gradual freezing of an underground ocean.
Either way, the 4.5 billion-year-old planet appears to be very much “alive” in a geologic sense.
As for the New Horizons probe, after coming within 7,700 miles of Pluto during the flyby on Tuesday, it is already more than a million miles beyond it.