The Solar System features profound size differences, with small, rocky worlds orbiting alongside enormous, gaseous spheres. Comparing Earth, a comfortable terrestrial planet, to the colossal ringed world of Saturn highlights this dramatic disparity in size. The question of how many Earths could be contained within the second-largest planet in the solar system reveals a startling perspective on planetary grandeur. This numerical comparison is the starting point for exploring the fundamentally different natures of these two worlds.
The Dimensions of Earth and Saturn
To determine the volume relationship between the two planets, it is necessary to establish their physical sizes. Earth possesses an average radius of approximately 6,371 kilometers, defining its volume as roughly \(1.08 \times 10^{12}\) cubic kilometers.
Saturn, by contrast, is a giant among the planets, with an average radius of about 58,232 kilometers. This makes Saturn nearly nine times wider than Earth. The sheer difference in radius translates into a massive discrepancy in overall volume.
Due to its rapid rotation, Saturn is not a perfect sphere; it is an oblate spheroid, flattened at the poles and bulging at the equator. Even accounting for this non-spherical shape, the volume of Saturn is vast, estimated at \(8.27 \times 10^{14}\) cubic kilometers. These figures provide the basis for the direct volume comparison.
The Core Comparison: Earths Inside Saturn
Comparing the volumes of these two bodies reveals the answer: approximately 764 Earths could be contained within Saturn. This calculation is a straightforward division of Saturn’s total volume by Earth’s total volume.
The figure 764 represents the number of Earth-sized objects that could theoretically be packed into the space Saturn occupies. This calculation relies on the scientific assumption that both planets are perfect spheres. It also assumes the Earth spheres could be perfectly compressed and stacked without any wasted space between them.
A mathematical packing scenario, where spherical objects are placed inside a larger spherical container, reveals a slightly lower number. Even with the most efficient sphere packing arrangement, the total number of whole, uncompressed Earths that could physically fit would be less than the volume ratio suggests, though still well over 700. The number 764, derived from the simple volume ratio, is the standard figure used to illustrate the impressive scale difference.
Beyond Volume: Why the Number is Theoretical
The impressive number of 764 Earths is a comparison of volume, not a literal stacking exercise that could ever be performed. The fundamental reason for this lies in the radically different compositions of the two planets. Earth is a terrestrial planet, defined by its high density of 5.52 grams per cubic centimeter and its distinct layers of a solid crust, mantle, and metallic core.
Saturn, conversely, is a gas giant, which means it lacks a solid, well-defined surface. Its average density is only 0.687 grams per cubic centimeter, which is less dense than water. The planet is composed almost entirely of light gases, with its atmosphere being about 96 percent molecular hydrogen and three percent helium.
A spacecraft descending into Saturn would not land on a hard surface but would sink through ever-hotter and denser layers of gas. The increasing pressure would eventually transform the hydrogen gas into a liquid metallic state, far below the visible cloud tops. This transition from gas to liquid to metallic liquid happens gradually, without distinct boundaries.
The theoretical nature of the comparison also overlooks the extreme pressures within Saturn. Any Earth-like object placed deep inside the gas giant would be crushed and vaporized by the immense pressure and heat. Scientists estimate the temperature at Saturn’s core, which is thought to be a dense, rocky body up to 22 times the mass of Earth, could reach 15,000 degrees Celsius.