GEO 101 1st Edition Lecture 1 Outline of Last Lecture 1 N A Outline of Current Lecture 1 What does a geologist do 2 Scientific inquiry or scientific method 3 Cosmology 4 Earth s changing place 5 An evolving image of earth 6 The renaissance 7 The solar system 8 The planets 9 Stars and galaxies 10 The Doppler Effect 11 Theory of the Expanding Universe 12 Big Bang Current Lecture What does a Geologist do Minerals exploration o Gold mining copper mining Hydrocarbon exploration o Oil gas exploration These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Environmental policy cleanup hydro coastal Civil engineering Research and Development Teaching secondary college Many careers opportunities for geologists Scientific Inquiry Science assumes natural world consistent predictable Goal discover patters in nature use knowledge to make predictions Collect data through observation and measurements Scientific Inquiry or Scientific Method Recognize problem Collect data Hypothesis tentative or untested explanation Theory well tested widely accepted view that scientific community agrees best explains certain observable facts Observation hypothesis theory Theory law Cosmology Study of the structure and history of the Universe Cosmology is a complicated science o Requires thinking in unfamiliar scales of space and time Spatial scales Attometers 10 21 meters to 10s of billions of light years 9 46 22 meters Temporal scales Attoseconds 10 21 seconds to 10s of billions of years 3 15 17 seconds Earth s Changing Place 3 000 years ago humans knew the heavens well o They knew stars were fixed relative to other stars o They knew that stars moved predictably across the sky o They knew retrograde motion separating planets from stars o They did not think of Earth of a planet however Movement in the heavens was attributed to deities or Gods An Evolving Image of Earth The ancients though the universe was Geocentric earth in center of universe o Heavenly bodies circle around motionless central earth o Proven by Ptolemy 100 170 A D the idea was wrong o The idea held as religious dogma for 1 400 years A heliocentric sun centered universe was proposed by the Greeks around 150 B C The Renaissance Rebirth of rational thought in 15th century Europe Spawned a new age of scientific discovery o Copernicus published evidence for heliocentricity o Kepler his elliptical planetary orbits o Galileo observed moons orbiting Jupiter o Newton planet motion explained by this Theory of Gravity Natural laws governed natural events Geocentricity faded away The Solar system Solar system a sun planets moons and other objects Earth shares the solar system with 7 planets a planet o Is a large solid body orbiting a star the sun o Has a nearly spherical shape o Has cleared its neighborhood of other objects Moon a solid body locked in orbit around a planet The solar system also includes asteroids and comets The Planets Two groups of planets occur in our solar system o Terrestrial earthlike small dense rocky planets Mercury Venus Earth Mars o Jovian Jupiter like large low density gas giant planets Jupiter Saturn Uranus and Neptune o Heavier planets are closer to the sun than lighter planets Pluto is no longer considered to be a planet The Solar System The Terrestrial planets are the 4 most interior The Jovian Plenets occupy the outermost orbits The asteroid belt lies between Mars and Jupiter o Basically divides the terrestrial from the Jovial planets Plenet orbital planes lie within 3 degrees of the sun s equator Stars and Galaxies Stars are immense balls of incandescent gas o Light and heat derives from nuclear fusion reactions o Gravity binds stars together into vast galaxies The solar system is on an arm of the milky way galaxy o Our sun is one of 3000 billion stars in the milky way o Milky way is only one of thousands and millions of galaxies The Andromeda galaxy s 2 2 million light years away o The speed of light c is 186 000 miles s The moon is 1 3 light seconds The sun is 8 3 light minutes away The Universe contains more than 100 galaxies Questions Science is the basis for addressing hard questions o How did the universe form o Do galaxies move with respect to each other o Is the Universe expanding Contracting o How do we know anything about these matters The Doppler Effect permits us to detect star motion o Lets us look at stars and determine if they re moving away us towards us or steady The Doppler Effect Waves compress or relax with relative motion o The stopped train sounds the same to Anna and Bill o The moving train sounds different to Anna and Bill Anna hears a higher pitch from compressed sound waves Bill hears a lower pitch from expanded sound waves As the train passes Anna the pitch drops higher to lower This is commonly heard as cars wiz by on a road The Doppler Effect for light Visible light is electromagnetic radiation o Visible wavelengths range from 400 700 nanometers 400nm blue higher frequency 700nm red lower frequency o Moving light waves compress blue or expand red The Red Shift A moving star displays Doppler shifted light o Approaching starlight is compressed blue o Receding starlight is expanded red Theory of the Expanding Universe Light from galaxies was seen to be red shifted o Hubble recognized the red shift as a Doppler Effect o He concluded galaxies were moving away at great speed o Curiously no galaxies were found heading towards Earth o The Expanding Universe Theory evolved Think of a loaf of raisin bread o As the raisin bread bakes and rises the raisins are spreading out Big Bang And expanding Universe When did it all begin Run the film movie backwards so to speak o The Big Bang All mass and energy in a single point o It exploded about 13 7 GA and has been expanding ever since During 1st instant only energy no matter present Started as a rapid cascade of events o Protons and neutron formed within 1 second o Hydrogen atoms by 3 minutes fused to form new light elements He Be Li B via Bing Bang Nucleosynthesis o The Universe expanded cooled and decreased in density With expansion and cooling atoms became to bond o Hydrogen formed H2 molecules the fuel of stars o Atoms and molecules coalesced into gaseous nebulae Gravity caused collapse of gaseous nebulae Collapse resulted in increases in o Temperature o Density o Rate of rotation After the Big Bang Condensed nebula formed flattened accretion discs Heat and mass