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Today I learn that Pluto and Charon are tidally locked to each other.

    > Charon always presents the same face to Pluto, and
    > Pluto always presents the same face to Charon: from 
    > any position on either body, the other is always at 
    > the same position in the sky, or always obscured
http://astronomy.stackexchange.com/questions/8427/are-there-...
Just to be clear: this is not a new discovery. The mutual tidal locking has been known experimentally for quite a while, and can be predicted with high confidence based on their sizes and distance.
Wow! The imagery is very quickly getting better now.