Pluto is the pits!

Pluto is the pits!  Well, Pluto has the pits – a lot of them!  The photo at right was taken by the New Horizons spacecraft during its July flyby of Pluto.  The pits are in a lake of frozen nitrogen, are up to a kilometer in diameter, tens of meters deep, and are not impact craters.  The current best guess is that they're areas where the nitrogen ice sublimated away for some (unknown) reason.  Just one of the many surprises uncovered by New Horizons!  Via APOD, of course...