Galileo's Pendulum

So Pluto has a fifth moon in orbit, temporarily designated P5, to accompany Charon, Nix, Hydra, and um…P4. (I guess someone will get around to naming P4 and P5 one day. I nominated “Fred” and “George”.) P5 is so tiny and faint that even our best instruments can only give it a maximum size: it’s…