AST 111 Lecture Notes - Lecture 21: Corona, Lithosphere, James Van Allen
18 Dec 2020
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Document Summary
Average density- ratio of its mass to volume is 5. 52 g/cm^3. We know about the density because of the travel times of two waves generated by earthquakes. P waves can enter all parts of the earth, and s waves can"t enter the liquid parts. Earth is made up of 4 parts. Crust- outermost part of the earth, and has a density ranging from 2. 5 and 3 g/cm^3. Mantle- thick, solid layer between the crust and the core. The outer core- composed of liquid metal. The inner core- centermost portion that ranges up to 13 g/cm^3. The increasing density of the earth is caused by the chemical differentiation, which was the sinking of denser metals when the earth was completely molten. Earth"s magnetic field is now believed to be located in the liquid outer core. The magnetic poles are not at the earth"s poles of rotation, because the magnetic axis is tipped about 13 degrees.
