 Claire (Lauren Ambrose (qv)) mentions at dinner that she has an  overnight astronomy thing for school, and Nate  (Peter Krause (I) (qv)) and David (Michael C. Hall (I) (qv))  cover for her. They then have a discussion about the planetary  status of Pluto (is it, or isnt it?). The same discussion occurred  on an episode of Peter Krause (I) (qv)s previous show,  _"Sports Night" (1998)_ (qv), between him and his co