Origin Of Earth Lecture 1 PDF

Objectives List the characteristics of planet Earth that make it habitable Explain the leading theories for the formation of the universe (Big Bang), and the solar system (nebular hypothesis) and Earth (planet accretion) Contrast the elemental composition of Earth, the Sun, and the Universe...

Objectives List the characteristics of planet Earth that make it habitable Explain the leading theories for the formation of the universe (Big Bang), and the solar system (nebular hypothesis) and Earth (planet accretion) Contrast the elemental composition of Earth, the Sun, and the Universe Explain why Earth’s structure is layered Identify the crust, mantle and core Discuss the formation of the Oceans and Atmosphere 1  Why does life exist on Earth? In pairs make a list of things about Earth that make it a good habitat for life? Do other planets have these resources? 2  Why does life exist on Earth? Water Goldilocks Theory: “Just Air/atmosphere/oxygen right” distance from star and Sunlight size The right temperature Nutrients Producers to make food Gravity Magnetic field https://exoplanets.nasa.gov/resources/323/goldilocks-zone/ 3  Comparison of Planets Table 1.1 on page 3 Distance from Equatorial Sun (millions diameter Density Planet of km) relative to (g/cm3) Earth Mercury 58 0.38 5.4 R O Venus 108 0.95 5.2 C K Earth 150 1.00 5.5 Y Mars 228 0.53 3.9 Jupiter 778 11.19 1.3 G Saturn 1427 9.41 0.7 A S Uranus 2870 4.06 1.2 E O Neptune 4479 3.88 1.7 U S Pluto 5900 0.23 1.1 from www.nasa.gov 4 Most scientists theorize that the universe began with the Big Bang around 13.8 billion years ago Estimates range from 10 - 27 billion years ago 5  Evidence for Big Bang Empirical and surrounds us: Abundances of primordial elements Expanding Universe Cosmic background radiation https://unctv.pbslearningmedia.org/resourc e/ess05.sci.ess.eiu.microwave/evidence- for-the-big-bang-theory/ 6  Formation of the Solar System The Solar System, including Earth, formed approximately 4.56 billion years ago Means the Solar System formed at least 9 billion years after the Big Bang Image: https://map.gsfc.nasa.gov/media/060915/index.html 7  Nebular Theory Solar system formed from the gravitational collapse of a giant interstellar gas cloud Spherical nebula begins to shrink and collapse; Gravitational potential energy is converted to heat. As radius decreases, it rotates faster 8 In this model, the masses accreting to form Earth are mostly unsorted lumps of FeO, MgO, and SiO2 9  Planetary Accretion Halliday, Alex N., and Robin M. Canup. "The accretion of planet Earth." Nature Reviews Earth & Environment 4.1 (2023): 19-35. 10 Giant Impact with Theia produced Moon & tilted axis http://www.astro.wisc.edu/~townsend/static.php?ref=diploma-4 11  Approximate Relative Elemental Abundances (% by mass) Universe Sun Bulk Earth’s Earth Surface What is the H 91 H 92.5 Fe 35 O 46 composition of Earth? He 9.1 He 7.3 O 30 Si 28 Is it similar in O 0.05 O 0.07 Si 15 Al 8 composition to the N 0.04 C 0.04 Mg 13 Fe 6 rest of the Universe? C 0.02 N 0.01 Ni 2.4 Mg 4 Is Earth Ne 0.003 Ne 0.007 S 1.9 Ca 2.4 homogeneous? Si 0.003 Mg 0.004 Ca 1.1 K 2.3 12  Conclusions If Earth formed from same material as rest of universe, it must have evolved Some process on Earth must be responsible for the concentration or redistribution of elements How did the unsorted, homogeneous Earth become heterogeneous? 13  How did the unsorted, homogeneous Earth become heterogeneous? Energy of accretion Gravitational compression Radioactive decay 14 Earth’s Layers Three main layers: 1. Crust 2. Mantle 3. Core Ordered by density Image: https://pubs.usgs.gov/gip/dynamic/inside.html 15 http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=51148 16  H2O + CO2   H2CO3 http://sdotblog.seattle.gov/2009/08/17/paving-quiz-%E2%80%93-what-do-crews-do-when-it-rains/ 17  Video: Evolution of Earth and Intro to Plate Tectonics https://www.youtube.com/watch?v=3sd6v QA3yws National Geographic program on plate tectonics Start at 4:46 and end at 15:30 18