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

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’S
LAYERS
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
• Composed primarily of Fe with some Ni. Represents
1.7% of earth’s mass. Temp is near 7000K but
material is solid because of intense pressure. Average
density is 13.5 g/cc.
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