Pluto’s first close-up reveals ice mountains and no craters

New York Times : The first close-up image of Pluto was released by NASA yesterday during its continued New Horizons press events. Two characteristics stood out: ice mountains the size of the Rockies and a complete lack of craters. The size of the mountains suggests they are probably made of frozen water because frozen methane and nitrogen are too weak to support the size and height, even in Pluto’s weak gravity. However, no previous observations of Pluto had detected any water, so the presence of the mountains was unexpected. The lack of craters was surprising; it indicates that the surface layer of the planet is relatively young at less than 100 million years old. However, as an icy body, Pluto was not expected to be tectonically active. What might have wiped the surface clean of craters is unclear. For icy moons such as Jupiter’s Europa, tidal forces from the parent planet are enough to drive tectonic systems. The tidal forces between Pluto and its largest moon Charon are not nearly strong enough for that.