Was anyone expecting an active geology? I read that some people were expecting a dead, more cratered Triton, but the lack of craters seems to have taken everyone by surprise. And yes atmosphere is being mentioned, and that can be a factor, but we are talking thinner than the Martian atmosphere here. Pluto is tiny, roughly 1/2 the diameter of the moon, and this preliminary data is showing it acting more like a comet than a planet. Can an atmosphere that thin erase that much geology? Or does Pluto get close enough to the sun every 200 years to melt the surface enough to reform the surface?Pluto has a very active geology. It is very possible that this event happened long enough in the past that all evidence has been wiped away, or covered by the deposition of ices from its atmosphere.