Final answer:
Saturn is the least dense planet in the solar system, with an average density lower than water. Its composition primarily consists of gases like hydrogen and helium. In comparison, planets like Jupiter, Neptune, and Mercury have higher densities.
Explanation:
Least Dense Planet in the Solar System
The planet with the least density in our solar system is Saturn. Its average density is about 0.687 grams per cubic centimeter, which is even less than that of water. This low density is due to Saturn's composition, which is primarily made up of gases like hydrogen and helium, resulting in a large volume with relatively little mass.
In contrast, other planets such as Jupiter and Neptune have higher densities due to their larger amounts of heavier elements and gases. Mercury, being a rocky planet, also has a higher density when compared to the gas giants. Therefore, when discussing the density hierarchy among the planets, Saturn is unique in its low density.
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