Lecture 3 Notes 8.29 - GS1004 Spotila 29 August 2016 Lecture 3 Building the Earth Earth's Interior Relevant reading Interlude D p 282-294 Chp 11 p

Lecture 3 Notes 8.29 - GS1004 Spotila 29 August 2016...

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GS1004 Spotila 29 August, 2016 Lecture 3: Building the Earth: Earth's Interior Relevant reading: Interlude D, p. 282-294; Chp. 11, p. 365-373 Motivating questions: It took ~100 million years to grow the Earth by planetessimal accretion, including a “giant impact”. But, it didn’t look like Earth now. What did it look like and why? How did it evolve, to have the structure it has today? How do we know this structure? Gravitational accretion by meteorite impact converted ... Potential energy into kinetic energy (heat). A meteorite traveling 20 km/s produces same energy as an equal mass of TNT. What did all of this heat do to the Earth? All of this heat softens and melts the Earth. Large bodies (even the Moon) are spheres because they are soft (hot) when they form (and gravity). What did we call this early Earth? “Hadean Earth” Differentiation : Earth differentiates by gravity by ~4.4 b.y. ago .... Dense liquid sinks to center, light floats near surface. Change from homogenous to compositionally layered. INNER CORE: From center to ~1200 km (1% by volume), solid, consists of iron and nickel, ~5000 °C. Only the inner core is solid OUTER CORE:
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