GEO L2 - The Universe and the Earth PDF

CIEN 203 | POLYTECHNIC UNIVERSITY OF THE PHILIPPINES WEEK 2: 2. ABUNDANCE OF HYDROGEN AND HELIUM Hydrogen and Helium THE UNIVERSE AND THE EARTH...

CIEN 203 | POLYTECHNIC UNIVERSITY OF THE PHILIPPINES WEEK 2: 2. ABUNDANCE OF HYDROGEN AND HELIUM Hydrogen and Helium THE UNIVERSE AND THE EARTH - first elements to form (simplest) - primary building blocks of stars and other gas clouds in FORMATION OF THE UNIVERSE AND THE the Universe EARTH 3. HUBBLE’S REDSHIFT THE BIG BANG THEORY Two discoveries that changed our perspective of the is the current prevailing theory for the beginning of the Universe: (Hubble, 1920’s) Universe 1) The Universe is larger than what we thought it was first proposed by Georges Lemaître in the 1920’s. (1923) 2) The Universe was getting bigger (1929) 13.7 BILLION YEARS AGO - The degree of galaxy’s redshift was proportional to its distance from us. If the Universe is expanding, it must have been THE SINGULARITY smaller in the past. an infinitely small region with virtually zero volume; but it contained everything in the universe THE SOLAR SYSTEM MATTER – ENERGY – SPACE – TIME were created THE NEBULAR HYPOTHESIS formation of the Solar System the hypothesis was first proposed by Immanuel Kant and Pierre Simon de Laplace in the 18th century. Inner and outer planets emerged, separated by the frost line. THE EVIDENCE 1. COSMIC MICROWAVE BACKGROUND (CMB) believed to be residual radiation from the Big Bang one second after the Big Bang, subatomic particles Inner/terrestrial planets: rocky, largely composed of scattered everywhere silicates and metals (Si, Fe, O) the Universe would have been opaque because free Outer/Jovian planets: lacks a solid surface, in gaseous or electrons would have caused photons to scatter liquid form, composed of lighter elements (H, He, Ar, C, O, N) COSMIC MICROWAVE BACKGROUND RADIATION (CMBR) THE SOLAR SYSTEM TO SCALE As everything eventually cooled down and the subatomic particles decayed and “recombined”, free electrons being absorbed to form neutral atoms, photons stopped being emitted and the Universe became transparent. - The afterglow of that event is the CMB. BS CIVIL ENGINEERING 2-2 1  CIEN 203 | POLYTECHNIC UNIVERSITY OF THE PHILIPPINES COMPOSITION OF MASS OF SOLAR SYSTEM THE EARTH Body % Mass Sun 99.85% ACCRETION Jupiter 0.10% All other planets 0.04% HEATING Comets 0.01% Satellites and rings 0.00% DIFFERENTIATION Asteroids 0.00% Meteoroids and dust 0.0000001% ACCRETION the dust would stick together due to gravity and slowly THE SUN accrete to form the Proto-Earth. middle aged star HEATING made up of hydrogen heating during this early stage lead to the melting of some materials and creating a molten earth. DIFFERENTIATION because the elements could move more freely in liquid form, the heavier elements sank towards the center of the Earth, THE PLUTO CONTROVERSY while the lighter elements rose to the surface. orbits the sun THE IRON CATASTROPHE has enough mass to be round Heavier: sank to the core has not cleared it orbit of debris Lighter: rose to the surface The sources of heat causing the proto-earth to melt: - Heat from collision - Radioactive decay - Solar radiation - Contraction THE MOON FUN FACTS FORMATION OF THE MOON: GIANT IMPACT HYPOTHESIS FUN FACTS Which planets have rings? - Saturn - Neptune - Jupiter Mercury - 0.1° Jupiter - 3° - Uranus Venus - 177° Saturn - 27° Earth - 23° Uranus - 98° Computational research: THEIA (Mars-sized planetesimal) Mars - 25° Neptune - 30° collided with the Earth and debris coalesced to form the Moon BS CIVIL ENGINEERING 2-2 2  CIEN 203 | POLYTECHNIC UNIVERSITY OF THE PHILIPPINES Thickness varies ORIGIN OF THE ATMOSPHERE (AND OCEAN - Continents: 15 – 60 km BASINS) - Oceans: 3 – 15 km - Less than ~1% of the Earth’s mass and volume. Important consequence of the Earth’s differentiation Occurred in stages: MANTLE 1) Primordial atmosphere lost to solar wind (4.5 Bya) Still iron-rich compared to crust, but diluted with oxygen, 2) Continual degassing and venting as the Earth silicon, magnesium, etc. differentiated (4.0 Bya) - 2,900 km thick 3) Steady accumulation of gases allowing the atmosphere - 83% of Earth’s volume to thicken - 68% of Earth’s mass 4) Build-up of oxygen from cyanobacteria and subsequently plants (3.5 Bya to Present) CORE Iron-nickel alloy iron rich sphere with small amounts of Ni and other elements FEATURES OF THE EARTH - 3,500 km in radius - 16% of Earth’s volume LAYERS OF THE EARTH - 31% of Earth’s mass MECHANICAL LAYERS Different Mechanical Layers COMPOSITIONAL LAYERS Compositional (chemical) layers are differentiated by the dominant lithology or chemical composition. Ex. Fe-Ni core vs. silica-rich crust The inner core is solid, while the outer core is liquid. Why is this the case? MECHANICAL LAYERS Variability in the different layers’ rigidity: differences in Mechanical (physical) layers are differentiated by their Temperature and Pressure rigidity or strength. - Increase in T: melting, increased fluidity, decreased Ex. Brittle lithosphere vs. ductile asthenosphere viscosity - Increase in P: solidification, increases interaction between molecules: compaction COMPOSITIONAL LAYERS - Rigidity: response of the material to the T&P condition at depth CRUST Solid outer shell LAYERS OF THE EARTH: THE EVIDENCE composed of: Mantle xenoliths: mantle rocks brought up to the surface by magmatic activity (physical) layers are differentiated by their rigidity or strength. BS CIVIL ENGINEERING 2-2 3  CIEN 203 | POLYTECHNIC UNIVERSITY OF THE PHILIPPINES Fe-Ni meteorites: leftovers from the formation of the Solar System; must have been one the building blocks of proto- Earth EARTH’S SIZE Equatorial circumference = 40,076 km Polar circumference = 40,008 km What 3D shape does that give the Earth? - Oblate spheroid. ERATOSTHENES calculated the Earth’s circumference as 41,000 km! Basic calculation: 𝐶𝑖𝑟𝑐𝑢𝑚𝑓𝑒𝑟𝑒𝑛𝑐𝑒 360 𝑑𝑒𝑔𝑟𝑒𝑒𝑠 = 800 𝑘𝑚 7 𝑑𝑒𝑔𝑟𝑒𝑒𝑠 THEORIES OF ISOSTASY ISOSTASY state of equilibrium between parts of the Earth’s lithosphere BS CIVIL ENGINEERING 2-2 4