Saturn has an average density of approximately 0.687 g/cm³ (or 687 kg/m³), making it the least dense planet in our solar system.

Yes! Liquid water has a density of 1.0 g/cm³. Because Saturn's mean density is only 0.687 g/cm³, Saturn would theoretically float if placed in a vast enough ocean of water.

Saturn is composed primarily of light volatile gases—roughly 96% hydrogen and 3% helium—with a huge extended atmosphere that inflates its total volume relative to its mass.

Earth is the densest planet in the solar system at about 5.51 g/cm³, meaning Saturn's average density is only about 12.5% (one-eighth) of Earth's density.

Yes, 0.687 g/cm³ is only an overall average. Its upper cloud layers are extremely light and diffuse, while its deep interior core compressed under immense pressure is estimated to be much denser.

Jupiter has an average density of 1.33 g/cm³, which is nearly double that of Saturn. Jupiter's superior gravity compresses its interior gases into much denser states.

Density is determined by dividing total mass by total volume ($\rho = \frac{M}{V}$). Saturn's mass ($5.68 \times 10^{26}\text{ kg}$) was calculated from lunar and spacecraft gravity measurements, divided by its volume ($8.27 \times 10^{14}\text{ km}^3$).

Because of its low fluid density and rapid rotational period (~10.7 hours), outward centrifugal force causes Saturn to bulge noticeably at its equator and flatten at its poles, making it the most oblate planet in the solar system.

Internal heat generated by slow gravitational compression and helium precipitation keeps gases expanded, preventing the upper gas layers from collapsing into a smaller, denser volume.

Descending into Saturn's atmosphere causes density and pressure to rise rapidly, smoothly transitioning gas into liquid hydrogen and eventually dense metallic hydrogen surrounding a rocky/icy core.