As one can see, minor planets and moons are mixed together, and moons overlap with the major planets.
I've included moment of inertia because it is a measure of amount of central concentration. The moment of inertia of some object around some axis is the sum of (mass of that bit) * (distance from that axis)^2 over every bit of that object. For a spherical one, it is the same in all directions, while for an equatorial bulge produced by spin, the moment of inertia for the spin axis is larger than for the equatorial directions. For definiteness here, I've used the polar moment of inertia.
Constant density: moment of inertia = 2/5 = 0.4
If the material has an equation of state of (pressure) ~ (density)^2 ("n = 1 polytrope") then its size is independent of its mass, something close to true of Jovian-mass planets.
Pd2: moment of inertia = (2*(pi^2 - 6))/(3*pi^2) = 0.261
Something called the Darwin-Radau equation can be used to estimate an object's moment of inertia from its departure from sphericity, its mass, its size, and its rate of rotation. This departure can be in shape (flattening) or in gravity. That usually gives very good results if the object is not too concentrated in its center, and in this case, that equation gives 0.263.
The Darwin here is Charles George Darwin, a grandson of the famous biologist.
Sources of values of moments of inertia:
- Precession: Venus, Earth, Mars
- Libration: Mercury, Moon -- oscillations around synchronous rotation
- Interior modeling: Jupiter
- Darwin-Radau estimates: (Jupiter), Saturn, Uranus, Neptune, Io, Europa, Ganymede, Callisto, Enceladus, Dione, Rhea, Titan
All also with the help of departures from sphericity of these bodies' gravity.