GEO 101 1st Edition Lecture 1Outline of Last Lecture 1. N/AOutline of Current Lecture 1. What does a geologist do? 2. Scientific inquiry or scientific method3. Cosmology 4. Earth’s changing place5. An evolving image of earth 6. The renaissance7. The solar system 8. The planets 9. Stars and galaxies 10. The Doppler Effect 11. Theory of the Expanding Universe12. Big Bang Current LectureWhat 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 starso They did not think of Earth of a planet, however- Movement in the heavens was attributed to deities or GodsAn 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.CThe 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 awayThe 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 shapeo 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 Jupitero 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 gaso 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 motiono The stopped train sounds the same to Anna and Billo 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 radiationo 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 lighto Approaching starlight is compressed (blue)o Receding starlight is expanded (redTheory 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 BingBang Nucleosynthesiso The Universe expanded, cooled and decreased