Solar system relative masses. Conceptual artwork showing the planets and Sun of our solar system as blocks of weights. Each solar system body is depicted in mass relative to the Earth. Pluto has the smallest mass compared to the Earth (0.002 times the Earth), whilst the Sun has the largest (332,831 times the Earth). The Sun contains 99.9 percent of the mass of the entire solar system. Mass is defined as the quantity of matter in a body as measured by its inertia. Masses can be compared to one another by weight of bodies at the same place.