Module 2: Earth's Internal Heat Sources

• Earth was formed about 4.6 billion years ago.
• The Earth was formed from the process of accretion wherein gasses and dust of cloud was attracted by gravitational energy.
• When these masses compacted it

  formed planetesimals.
• Earth is considered as thermal engine since its main source of internal heat

  come from the produced decay of some naturally occurring isotopes from its interior.
• Radioactive decay is the spontaneous breakdown of an atomic nucleus causes the release of energy and matter from the nucleus.
• Some of the isotopes are potassium – 40, Uranium - 235, Uranium - 238

  and Thorium - 232.
• The pressure near the center of the Earth is considered to be 3 to 4 million times the pressure of atmosphere at sea level.
• Due to increase in pressure and presence of heavier materials towards the earth’s center, the density of earth’s layers also increases.
• The inner core as the inner most layer is composed primarily of iron and nickel which contributes to the density in the core that ranges between 12,600-13,000 kg/m3.
• primordial heat - the internal heat source from Earth’s early formation stage
• radioactive - an element that is capable of producing radiation
• pressure - increases due to the force pressing on an area because of the weight of an overlying rocks
• inner core -Earth’s inner most layer that is composed primarily of iron and nickel
• It took a long time for heat to move from the internal part of the Earth

  going to its surface.
• There had been convection transport of heat within the core to the mantle of the earth.
• Radioactive decay emits heat energy that prevents the Earth from completely cooling off.
• The escape of heat from Earth’s surface is less than the heat generated from internal gravitational attraction, so heat builds up with.
• Molten material under tremendous pressure conditions acquires the property of a solid and is probably in a plastic state.
• The inner core intense pressure prevents the iron and other minimal

  amount of some elements from melting.
• The pressure and density are simply too great for the iron atoms to move

  into a liquid state.