PLUTO-PALOOZA

Explanation: PLUTO-PALOOZA presenters Randy Monroe (left) - whose "Pops," Jim Christy, discovered Pluto's giant moon, Charon (named, in part, to honor Jim's wife and Randy's Mom, Charlene) - Mark Showalter, Tiffany Finley and Jeff Moore (extreme right), on stage during Astronomy Day at the California Academy of Sciences, April 25th, 2015.

Pluto

Image credit: Lee Hobson, Johns Hopkins University Applied Physics Laboratory.