SOLAR SYSTEM

Detailed explanation-1: -The mantle, which contains more iron, magnesium, and calcium than the crust, is hotter and denser because temperature and pressure inside the Earth increase with depth. As a comparison, the mantle might be thought of as the white of a boiled egg.

Detailed explanation-2: -Overall, the crust is less dense than the mantle, and basically “floats” on it. “granitic.” Oceanic crust is largely basaltic, of course; its mean density is higher, at about 2.8 g/cm3.

Detailed explanation-3: -The crust is made of solid rocks and minerals. Beneath the crust is the mantle, which is also mostly solid rocks and minerals, but punctuated by malleable areas of semi-solid magma.

Detailed explanation-4: -Earth’s interior layers are ordered by density. The densest layer is the solid metal inner core, the mantle is of intermediate density, and the least dense layer is the lithosphere, particularly the continental lithosphere. The origin of these layers and how scientists know about them is fascinating.

Detailed explanation-5: -Three centuries ago, the English scientist Isaac Newton calculated, from his studies of planets and the force of gravity, that the average density of the Earth is twice that of surface rocks and therefore that the Earth’s interior must be composed of much denser material.

Detailed explanation-6: -So the densest materials are pulled closer to the very center of the Earth while less dense layers settle further away from the center. The inner core is at the center of the Earth because it is the densest, made of solid iron and nickel.