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GG101 – Physical Geology Dr. Fletcher POST 721 [email protected] 956 2582 956-2582 Core Concepts Text – Lutgens and Tarbuck, 2009 You will inherit Earth. •Three exams, 70% total •In-class projects, homework, 25% total •In-class participation and attendance, 5% Big Island Field Trip http://www.soest.hawaii.edu/coasts/lecture/gg101/index.html How is science done? #1. Earth scientists use repeatable observations and testable ideas to understand and explain our planet. How old is Earth? #2. Earth is 4.6 billion years old. 1 What is Earth? How does Earth behave? #3. Earth is a complex system of interacting g rock,, water,, air,, and life. #4. Earth is continuously changing. changing What is special about Earth? What is life's role on Earth? #5. Earth is the water planet. planet #6. Life evolves on a dynamic Earth and continuously modifies Earth. 2 What is the human relationship to Earth? #7 Humans #7. depend on Earth for resources. What are natural hazards? #8 Natural #8. hazards pose risks to humans. What is the human impact on Earth? Some observations about the Universe #9 Humans #9. significantly alter Earth. 3 Observations of the universe If the universe were infinite and uniformly filled with stars and galaxies, the sky should be brilliantly lit at all times and the radiation would heat Earth and other celestial bodies thousands of degrees. Observations of the universe Those “stars” you see at night – they are mostly galaxies each with billions of stars. Is the universe infinite? It gets dark at night because the universe is not infinite. Because it takes time for light to travel from distant galaxies to Earth we see these galaxies as they were in the past, not as they are in the present. g of distant This image galaxies is a look backward in time. “Olber’s Paradox” Observations of the universe Edwin Hubble Discovered Galaxies beyond the Milky Way and the Cosmic red shift – Hubble’s Law Red Shift Red Or Orange ange Yellow Green Blue Indigo Violet Retreating g light source Stationary y light source Approaching pp g light source Galaxies that are furthest away, are retreating faster. This is typical of an expanding object. Analogy of the ambulance, train whistle, car on highway •Most galaxies are red shifted 4 In an unchanging universe galaxies would move randomly with respect to the Milky Way (a) and there would b no correlation be l ti between distance and rate of movement (b). In an expanding universe all galaxies would be moving away from each other (c) and the recession velocity would increase for galaxies with greatest distance (d). 15 km/sec 1mly Measurements of the red shift of distant galaxies provide data for calculating the value of “Hubble’s Constant” the cosmic rate of expansion. 30 km/sec 2 mly Edwin Hubble Edwin Hubble calculated the rate (R) at which the universe is expanding. R~15 km/sec for two galaxies that are separated by a distance (D) of 1 million light years (9.46x1018 km). R= D/T R t off expansion Rate i = di distance t between b t two t objects/time bj t /ti off expansion i This can be reorganized to T = D/R. T=age of the universe! Dividing D by R yields 6.3 x 1017 seconds or 1.99 x 1010 years. About 20 billion years. The Milky Way Galaxy, one of billions of other galaxies in the universe, i contains about 400 billion stars and countless other objects. Why is it called the “Milky Way?” Improvements in estimating the rate of recession have lowered the probable age of the universe to the range 13 to 14 billion years. Therefore - the Universe had a beginning – The “Big Bang” 5 Origin of the Solar System Solar Nebula Hypothesis The beginning of the Solar System 6.9 billion years ago – nebula formation An ancestral star – ended its life: Red Giant Explosion - Nebula Formation of a nebula Nebula Collapse and Condensation Rotation started by shockwaves from a nearby explosion (?) Because the solar nebula was rotating, it contracted into a disc, and the planets formed with orbits lying in nearly the same plane. 6 The spinning solar nebula segregated into a cooling outer t accretion ti disc di off rocky fragments and dust, and the inner nebula core that was to become the Sun Planetesimal accretion - ~5 to 4.6 billion yrs ago Volatile compounds expelled from inner system (He, H, CO2, H2O, N2, CO, NH3, CH4) Inner system enriched in Fe, Si, O, Mg, Al, Ca + others Inner Rocky Planets – Fe, Mg, Si, O, Ca, Na, K, Al (nonvolatile) Outer Gas Giants – He, H, CO2, H2O, N2, CO, NH3, CH4 (Ices) (volatiles) 7 Comet Tempel, 19 seconds before impact Dust tail from trajectory Ion tail from solar radiation Edgeworth-Kuiper belt and Oort Cloud Oort Cloud and Edgeworth Edgeworth-Kuiper Belt of comets Inner Rocky Planets…………Outer Gas Giants Mercury – no atmosphere So heat is not retained Daytime temp +230deg., But night temp -140deg. 8 Venus, heavy g greenhouse effect, enough to melt many metals. Carbon dioxide 96% of atmosphere…temp 480 deg Channels are formed by running water, Probably from melting ice – not rainfall 9 Jupiter's Great Red Spot - A hurricane the size of Earth lasting several centuries Does Jupiter have a hard surface? No hard planet may allow for different winds at different speeds – hence, banding Saturn, in the center, is shown with eight g of its moons. The Uranian system showing Ariel in the forefront, with Uranus rising behind. Traversing clockwise from Ariel are the satellites Umbriel, Oberon, Titania, Miranda, and the small moon Puck. 10 Pluto. A rare image of tiny Pluto with its moon Charon, which is slightly smaller than the planet. Pluto has not yet been visited by any spacecraft, it remains a mysterious planet. Pluto's surface is believed to reach temperatures as low as -240°C (400°F). From Pluto's surface, the Sun appears as only a very bright star. Early Earth Near Moon… Earliest phase of Earth heating heating… 11 12