Earth's Interior: How Hot Is It? PDF

# EARTH'S INTERIOR ## How hot is the Earth's Interior? The table below will help you visualize and understand the composition and structure of the Earth's interior. It provides you scientific knowledge that will help you describe the different layers of the Earth as well as understand their chara...

# EARTH'S INTERIOR ## How hot is the Earth's Interior? The table below will help you visualize and understand the composition and structure of the Earth's interior. It provides you scientific knowledge that will help you describe the different layers of the Earth as well as understand their characteristics. | Layer | Thickness | Density (g/cm³) | Temperature (°C) | Composition | |--------------|-----------|-----------------|-------------------|------------------------------| | Inner Core | 1255 km | 12.6-13 | 4760 | Solid Fe & Ni | | Outer Core | 2220 km | 10-12 | 3871 | Liquid Fe & Ni | | Mantle | 2900 km | 3.3-5.7 | 1260-3000 | Fe, Mg & Si | | Crust | 38.5 km (ave) | 3.1 (oceanic) | 870 | O2, Si, Al, Fe, Ca, Na, K, Mg | Scientists tried to explore and study the interior of the Earth. Yet, until today, there are no mechanical probes or actual explorations done to totally discover the deepest region of the Earth. We will explore and dig into the interiors of the Earth from the outer most layer which is the crust, then the mantle and finally the core-outer core and inner core. Out from these layers, you will try to discover how heat inside the planet is produced and its importance to the existence of all living beings. ## Sources of Earth's Internal Heat Convection is one of the reasons of the heat in the earth's interior. The process tells us that the heat in the earth's internal is redistributed. The less dense material rises and more dense material sinks. Convection occurs at the upper mantle where hot rock rises and slightly cooler rock sinks. The heat driving mantle convection has three main sources namely: 1. **Primordial Heat** The general term for the heat imparted to a planetary body by the processes of its formation and differentiation. It has three major components: * **Accretional Heat**: This is the heat generated by the conversion of the kinetic energy of impacting bodies to thermal energy. It is concentrated at the surface. * **Gravitational Release**: The gravitational potential of dense materials is converted to heat during differentiation. As iron, for example, "falls" to the center of the differentiating body, its movement gives rise to friction that releases heat according to the formula: Energy E = GMm/r, where G is the gravitational constant, M and m are mass, and r is distance from the center. Thus, once the heat of accretion gets differentiation going, it causes a positive feedback with the heat of gravitational release, releasing more heat. * **Frictional Heating caused by denser core material sinking to the center of the planet.** The descent of dense iron-rich material from the core to the center of the Earth creates heat. 2. **Radiogenic Heat**: the heat given off when radioactive elements in the earth's interior decay. A decisive role is played by the long-lived radioactive isotopes uranium-235 (235U), uranium-238 (238U), potassium-40 (40K), and thorium-232 (232Th) in Earth's mantle are the primary source of radioactivity. The amount of these elements in the earth is usually estimated according to the content of meteorites, based on the assumed similarity of the composition of meteorites to the composition of the earth's mantle and core. 3. **Tidal Friction**: one last ongoing source of planetary heat comes from tidal forces. We have discussed the nature of tides already, but not their effect on objects that experience them. In a nutshell: Whenever a tidal bulge is raised, frictional heat is generated. If a large bulge is being raised in solid material, considerable frictional heating results.