Answer:
densest planet
Step-by-step explanation:
The Earth is the densest planet in the Solar System, at 5.51 g/cm3, as others have correctly answered. The reason for this high density is the apparent collision, over four billion years ago, of a proto-Earth and a hypothetical Mars-sized planet Theia.The two planets collided and melted together, the iron common to both sank into the center of the Earth, and the lighter rocks (mostly granite) were thrown off and eventually congealed as the Moon, which has a density of 3.34 g/cm^3. (Granite has a density of 2.75 gm/cm^3). So the heavier material from both planets remained within Earth, and the lighter materials from both planets became the Moon. Water by definition has a density of 1 gm/cm3. The planet Saturn, by the way, has an *average* density of 0.69 gm/cm3, which is about the density of oak.
saw in another page explantation not mine