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Bell Work 9/8/2011 Chapter 2 in the Oceanography textbook is entitled “Origins”. What might we be studying the “origins” of in this chapter? Oceans Solar System Earth Moon Universe Atmosphere Origins – Oceanography Chapter 2 Part 1: Origin of Universe & Galaxies Big Bang Theory • Event that occurred approximately 14 billion years ago. • All mass & energy was concentrated at a geometric point. • The Big Bang marks the beginning of space and time. Evidence Supporting the Big Bang Theory 1. 2. 3. 4. Expansion of the universe. Cosmic Background Radiation. Nucleosynthesis of light elements. Formation of galaxies. ELECTRO-MAGNETIC SPECTRUM Smallest wavelength Largest wavelength What we see with our eyes Looking at the Crab Nebula with the EM Spectrum UV MW IR RADIO X-RAY VISIBLE Expansion of Universe Red Shifted = moving away Blue Shifted = moving towards 90% of all stars & galaxies observed are moving away from the Milky Way Cosmic Background Radiation • Ancient universe had small variations in temperature. • Over 14 billion years, gravity magnified these small differences into clusters of galaxies today. A sky map of cosmic background radiation (microwave) taken by NASA’s satellite called COBE. Scale & Structure in Universe Universe is composed of voids and galaxy clusters. Voids could be millions of light years across. Nucleosynthesis of Light Elements • Hydrogen atoms: – the most common form of matter in the universe. • Atoms have mass. Clump together under gravity. • Formation of elements: – He through Fe (iron) inside stars (nuclear fusion) – Heavier elements in supernova explosion (Fe & beyond) Formation of Large-Scale Structures Galaxies, like our Milky Way, are composed of stars, dust, gas and debris held together by gravity. Galaxies The Milky Way is approx. 100,000 light years in diameter. Our solar system is located on an outer spiral arm 27,000 light years from the galactic bulge. A black hole may be found within the bulge of the galaxy. Types of Galaxies Irregular Galaxy Spiral Galaxy Elliptical Galaxy (globular cluster) More Types of Galaxies Part 2: Origin Stars (Life Cycle of a Star) Life Cycle of a Star Life Cycle of a Star Step 1: All stars are born in nebulae. • Nebulae are clouds of dust & gas within galaxies. • Nebulae are concentrated in the arms of spiral galaxies. Types of Nebulae Supernova Nebula Dark Nebula Proto-stars • Proto-stars grow as hydrogen & helium gas are pulled together by gravity. • Proto-stars are not hot enough for fusion to occur. Artists rendition of a protostar As material continues to collect, the protostar gets hotter and hotter and hotter until . . . . . . Gamma & Xrays Nuclear fusion begins and blows off the remaining gas (our first atmosphere)! Stage 2: Main Sequence Star Our sun is a main sequence star (stable). It is a yellow dwarf star. Nuclear fusion of hydrogen gas into helium gas powers our Sun. Equation of Fusion e = mc2 4 H + 2e- 1 He + 2 + photons This is the nuclear reaction that happens inside stars and gives off massive radiation. All elements up to iron form inside stars, the remaining elements form during a supernova explosion. Bell Work 9-11-12 What event in a star’s life cycle changes a proto-star into a main sequence star? Nuclear Fusion occurs when the core temperature = 10 million degrees Kelvin Stage 3: Red Giant Stage • Hydrogen in the core is used up and fusion no longer balances gravity. • Star expands and collapses. • Gravity wins! Red Giant Stage - Unstable Stage 4 – Nova Stage Stage 5: White Dwarf Stage • All fuel is used up. • Dim, faint with high temperature. • Some Sun-like stars become white dwarfs made of carbon. • Some white-dwarfs flare up to a nova. Bell Work 9-12-12 Where do the following elements form? Hydrogen . . . Big Bang Helium to iron . . . Inside stars Elements heavier than iron . . . Supernova explosion Types of Stars Cool & Bright Hot & Bright Dying stars Our sun Dead stars Hot & Dim Cool & Dim HR Diagram Bell Work 9-13-12 Besides having life and abundant liquid water, what makes Earth different from the other terrestrial planets? Large moon Magnetic field High Density Plate Tectonics (volcanoes) Part 3: Origin of the Solar System Condensation Theory •The condensation theory explains how stars & planets are believed to be formed. •Condensation theory is based on the observation of stars and planets at different stages of development. •Scientists have inferred a sequence in which these stages occur. Origin of Our Solar System Metals (Fe, Mg, Al, Mn) & Rock (Si, K, Ca) – high melting points Gases like methane (CH4) and ammonia and solids like ice – low melting points 5 billion years ago: A solar nebula + shock wave & heavy atoms from a supernova= formation of solar system. Formation of Planets Terrestrial planets Planet formation Gas planets •New planets formed by a process called accretion, the clumping of small particles into large masses. •Accretion lasted about 30 to 50 million years. •As the sun began nuclear fusion, solar radiation swept past the inner planets clearing excess particles and stopping the accretion process. Our Solar System • Eight planets, asteroid belt, and icy bodies revolve around a star (our sun) in a plane. • Planet composition: – Inner 4 planets are terrestrial (rock/metal) – Outer 4 are gas giants (gas/ice) • Beyond Neptune are icy bodies (including Pluto) and asteroids. Terrestrial Planets Terrestrial planets are small, dense, and composed of rock. Venus is the hottest planet in the solar system due to runaway greenhouse effect. Mercury is a small, hot planet made mostly of iron. More Terrestrial Planets Mars is a dead planet with little atmosphere & evidence of liquid water on it’s surface. Terrestrial planets have few or no moons and no rings. Gas Planets Gas Planets are large, with low density, and composed of methane & ammonia gas. More Gas Planets Uranus & Neptune get their blue color from methane gas. Gas planets have lots of moons, rings, and no craters. Moons of Gas Planets Europa Moons of Gas Planets Titan Lakes of liquid methane Bell Work 8-27-13 What process was responsible for planet building? Accretion!! Part 4: Origin of the Earth, Atmosphere & Oceans Formation of Earth’s Crust Moon Formation 4.6 billion years ago Earth’s crust was partially melted by: • asteroid impacts • gravitational compression • decay of radioactive elements Moon’s importance!! Added large amount of material & radioactive heat to Earth’s mass. Kept our core molten = magnetic field. Formation of Earth’s Crust Density stratification of the Earth: • dense material like iron & nickel sank to form the core Rocky crust Fe & Ni core Layered or stratified Earth • light material like silicates (SiO2) magnesium, and aluminum forming the crust. Also called the “Iron Catastrophe” Formation of the Ancient Atmosphere Burp!! SO H2 O 2 CO 2 Earth's interior was heated primarily from decay of radioactive elements causing volcanism. Volcanic eruptions spewed gases from Earth's interior into the atmosphere, a process called out-gassing. Most of the gas was carbon dioxide and water vapor. Formation of Modern Atmosphere Other 1% O2 21% N2 O2 Other About 3.5 billion years ago the primitive atmosphere changed: CO2 dissolved into young ocean to form carbonic acid & combining with crustal rocks. N2 78% Oxygen Revolution 2 billion years ago Earth’s first ever revolution!! Oxygen began to accumulate in the atmosphere with the evolution of plants!! Burp O 2! Stromatalites – blue-green algae Ancient Modern Formation of Ocean Floor • Two types of Earth’s crust: – Ocean Crust (basalt) – Continental Crust (granite) • Ocean crust is more dense and thinner. • The tectonic processes formed the sea floor. Formation of the Ocean Forming about 4.2 billion years ago, the oceans water originated from: • Volcanic out-gassing continued until the atmosphere contained ~40% water vapor. • Additional water may have come from comets. Earth cooled, water condensed and formed the oceans. Out-gassing continues today. Volcanic out-gassing from volcanically active areas like Yellowstone & Mammoth Lakes