But Dick posits that “the density of Jupiter is little more than that of water, and that of Saturn about the density of cork.” Jupiter, therefore, would have a gravity only twice as great as Earth’s—not so terrible in the grand scheme of things...
Well, that’s kind of close. The average density of Saturn is in fact less than that of water, and the gravity at its cloudtops is only very slightly higher than at Earth’s surface. Jupiter’s isn’t that bad, either, at ~2.5g.
Sure, but that’s not impressive and you’d expect him to be close to right about those numbers. As I understand it, it’s pretty easy to derive the volume of planets from optical observations of diameter, and the mass from their orbits & Newtonian mechanics, and then divide to get net density.
Well, that’s kind of close. The average density of Saturn is in fact less than that of water, and the gravity at its cloudtops is only very slightly higher than at Earth’s surface. Jupiter’s isn’t that bad, either, at ~2.5g.
Sure, but that’s not impressive and you’d expect him to be close to right about those numbers. As I understand it, it’s pretty easy to derive the volume of planets from optical observations of diameter, and the mass from their orbits & Newtonian mechanics, and then divide to get net density.