20 x Jupiter by how big compared to our newest dwarf planet Pluto?
Hey, what is this, stump the 'Civ? :')
I think that Jupiter is 318 times the size of Earth, and Pluto is, hmm, a bunch smaller than Earth. Looks like wikipedia has it at 1/500 the mass of Earth (the estimate of its density was made possible by the discovery of its moon, Charon; that density figure and mass will probably be adjusted when the probe arrives).