The Earth's interior is hot due to two main sources of heat: primordial heat generated during Earth's formation from the condensation of gas and dust particles, and radioactive heat generated by the long-term radioactive decay of uranium, thorium, and other radioactive elements in Earth's core. These heat sources have not dissipated completely, accounting for about 10% of total heat still inside the Earth and causing volcanic eruptions at the surface.

2. LEARNING COMPETENCY
Explain why the Earth’s interior is hot
(S11/12ES-IIb-c23)

3. Have you seen those hot materials
coming out of the volcano?

4. The Earth's interior is
composed of four layers . . .

5. Primordial Heat
Heat generated during Earth’s
formation.
Primordial Heat
Heat generated during Earth’s
formation.

6. Earth is thought to have
arisen from a cloud of gas
and dust in space. Solid
particles, called
“planetesimals” condensed
out of the cloud.

7. The Earth
was formed
by the
process of
accretion.

8. This heat has not
dissipated totally and
represents about 10% of
the total heat inside the
Earth.

9. Radioactive Heat
Heat generated by long-term radioactive decay.

10. "Geoneutrinos" are electron antineutrinos produced by beta-decays of the
nuclei in the decay chains of 238U and 232Th.