What I find interesting is how few craters there are compared to other planets (yes I know pluto is no longer a planet). Does this reflect that meteor bombardment is rare in the outer solar system, or that there is some sort of geological process going on that is removing craters?
Initial interpretation of the first image apparently suggested an active (geologically speaking) surface. This would tend to remove visible craters. Think Venus (highly active surface) vs the Moon.
I'm not sure. I did wonder about this interpretation myself. It does not make much sense in terms our understanding of tectonics (or lack thereof) for other bodies in the solar system.
Would it be so round were this the case? I assumed it would take a long time for gravity to make a planet's surface round, much longer than it would take to accumulate a bunch of impact craters.
It would be rounded almost instantly. In an impact of that size -- almost exactly comparable to the impact which created the Earth-Moon system -- the surface of Pluto would have been heated so extensively as to become molton rock.
