Earth’s Internal Heat

If you think about a volcano, you know Earth must be hot inside. The

heat inside Earth moves continents, builds mountains and causes earthquakes. Where does

all this heat inside Earth come from?

Earth was hot when it formed. A lot of Earth’s heat is leftover from when our planet formed, four-and-a-half billion years ago.

So Earth started out with a lot of heat.

Earth makes some of its own heat.

Earth keeps a nearly steady temperature, because it makes heat in its interior.

The process by which Earth makes heat is called radioactive decay.

Uranium is a special kind of element because when it decays, heat is produced. It’s this heat that keeps Earth from cooling off completely.

• Earth’s core temperature is estimated to be around 5,000 to 7,000 degrees Celsius.

• That’s about as hot as the surface of the sun, but vastly cooler than the sun’s interior.

THE EARTH’SLAYERS

Relative Densities of Earth’s layers

• Continental Crust: 2.7 to 3.0 • Oceanic Crust: 3.0 to 3.3 • Asthenosphere (Mantle) 3.3 to 5.7 • Outer Core (liquid): 9.9 to 12.2 • Inner Core (solid): 12.6 to 13.0

Thickness of the Earth’s Layers

Temperature of the Earth’s Layers

Crust• The crust is less than 1% of Earth by mass.• Cold, thin, brittle outer shell made of rock.

Mantle• Made of solid rock and it is hot• It is composed of three parts lithosphere,

asthenosphere, and mesosphere.

Lithosphere, Asthenosphere

Mesosphere

Core• two parts outer core and inner core• Dense metallic center of the Earth

Outer Core• Molten metal

Inner Core• Solid metal

Heat flows in two different ways within the Earth.

Conduction• Heat is transferred through rapid collisions of

atoms.• Heat flows from warmer to cooler places until

all are the same temperature. • The mantle is hot mostly because of heat

conducted from the core.

Convection• the movement caused within a fluid by the

tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat.

Convection