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Cosmic Influences On Earth Big Bang • Estimated to have occurred 13.7 ± 0.13 billion years – WMAP (Wilkinson Microwave Anisotrophy (variation in temperature) Probe – Mapping Universe • Big Bang – 3.47min http://www.negotiationlawblog.com/Big%20Bang.jpg Concepts in Cosmology • Big Bang Theory: – Leads to a point of common origin for all matter – This point of common origin is where everything came into being in a single instant – Because time and space originated in the Big Bang, it did not occur in any specific location of space – Every point in the universe was there when the Big Bang occurred, and therefore, every point in the universe is where the Big Bang happened – The cosmic microwave background radiation is the echo of the Big Bang. Concepts in Cosmology • Big Bang Theory: (cont) – As the universe expanded, the wave stretched-out, much like a phone cord is stretched as you walk away from the base – The stretched-out wave would be very long and have very low energy – Two scientists, A. Penzias and R. Wilson, discovered this radiation, experimental verification of the Big Bang. 2 billion years after the big bang http://apod.nasa.gov/apod/ap960907.html Concepts in Cosmology • Future of the Universe – Big Crunch: If universe is greater than the critical density, collective gravity of all the matter in the universe will stop expanding and begin to contract. – Expanding Universe: If universe less than the critical density (current scientific theory), then universe will expand forever. http://apod.nasa.gov/apod/ap080210.html Universe • Our universe is estimated to have 125 – 500 billion galaxies • The average number of stars per galaxy is given as 200 billion • Error??? • Big 2.10 min http://www.astro.uio.no/ita/nyheter/HUDF_0304/HUDF_IR_full.jpg Two Inch Universe • If the Solar System is shrunk to 2 inches in diameter, then – The nearest star is 2 football fields away – The nearest star known to have planets is 6 football fields away – The Milky Way galaxy is the size of North America http://upload.wikimedia.org/wikipedia/commons/thumb/1/17/Alpha_Centauri_relative_sizes.png/800px-Alpha_Centauri_relative_sizes.png Milky Way • Starting with ours – the Milky Way • In a plane, the center found in the Sagittarius Arm • Silly name??? http://www.digitalskyllc.com – Nyx, goddess of the night sky, dripped milk • SS in MW http://www.youtube.com/watch?v=S7GiZMVNB20&feature=related http://hubblesite.org/gallery/album/entire_collection/pr2004025a/web_print Our Solar System • Medium size sun • 8 planets – – – – 4 rocky inner planets 4 gas giants 5 dwarf planets Asteroid Belt between last rocky and first gas giant – Kuiper Belt, of which Pluto is a large member – Oort Cloud http://upload.wikimedia.org/wikipedia/commons/c/c4/Planets2008.jpg Theories of Life • SETI (Search for Extra-Terrestrial Intelligence) – Life, including intelligent life, is found everywhere in our galaxy as well as other galaxies • Rare Earth Hypothesis – Most solar systems not suitable for life, but only in narrow habitable zones http://cache.io9.com/assets/resources/2008/04/SETI.jpg Drake’s Equation • R* = 10/year (10 stars formed per year, on the average over the life of the galaxy) • fp = 0.5 (half of all stars formed will have planets) • ne = 2 (stars with planets will have 2 planets capable of supporting life) • fl = 1 (100% of these planets will develop life) • fi = 0.01 (1% of which will be intelligent life) • fc = 0.01 (1% of which will be able to communicate) • L = 10,000 years (which will last 10,000 years) • N = 10 × 0.5 × 2 × 1 × 0.01 × 0.01 × 10,000 = 10, or the number of advanced civilizations. Drake’s Equation • Huge assumptions – which will greatly change the estimated number of intelligent civilizations in a galaxy • Range from 2.31 to 10,000s http://poweroftheunknown.files.wordpress.com/2006/04/drake2.jpg Habitable Zone • Where do we look? – Not too hot – Not too cold – Just right http://www.art.com/asp/sp-asp/_/PD--10100681/SP--A/IGID--1287057/Goldilocks.htm?sOrig=CAT&sOrigID=7645&ui=04CC46E750A7403884872C1AA8D89201 Habitable Zones • Greatest diversity and density of life found on our planet as we approach the equator Amphibiaweb.org/amphibian/countydata.html Habitable Zones • Only life known is Earth – Possible Mars – Possible satellites around Jupiter or Saturn • However, are those too cold • Possible when sun swells??? http://www.star.le.ac.uk/edu/Extrasolar.shtml Habitable Zones • Not only on Earth and in our solar system, but also in our galaxy – Too close to the center of the galaxy, too much radiation – Too far out on an arm, not enough radiation http://forgetomori.com/wp-content/uploads/2007/08/galactic-habitable-zone1.jpg Proof? • The only confirmation of life is on Earth • Distance to the farthest reaches of our observable universe is 46.5 billion light years • Billions of galaxies with billions of stars • Far fetched to think we are alone, but technologically intelligent life????? http://img159.imageshack.us/img159/6331/phpkahgjyamqo0.jpg Back to Earth • What cosmic influences can impact (literally) the Earth? • Meteors • Asteroids • Comets • Sun • Moon • Earth http://prehistoricsillustrated.com/images_kc/earth_impact.jpg Asteroid Belt • Total mass smaller than our moon (but much of the mass lost) • 26 large and millions of small asteroids • Ceres largest, now classified as a minor planet http://www.arcadiastreet.com/cgvistas/ceres_100a.htm http://www.semp.us/_images/biots/Biot443PhotoA.jpg Oort Cloud • Outer reaches of our solar system from Kuiper Belt to ~50,000AU! • Billions of comets http://astro.berkeley.edu/~conor/ay250/pluto.html Sun • Medium yellow star • ~10 billion life span • Primarily hydrogen with some helium • Converts ~8 tons of matter per second to energy Flare E = mc2 http://apod.nasa.gov/apod/ap051005.html Size 1 Size 2 Energy Output • Sun produces so much energy, that one second is equivalent to the the current energy used by world for 500,000 years • Most of the energy is xray, ultraviolet, visible, and infrared plus subatomic and charged particles http://dawn.artov.rm.cnr.it/img/spectrum.jpg Gravity • From Newton to Einstein • Spacetime and Gravity Earth in Space • Earth protected by magnetic fields – Generated in outer liquid iron/nickel core • Earth protected by atmosphere – Screens gamma rays, x-rays and most ultraviolet rays http://lpmpjogja.diknas.go.id/kc/e/earth_files/earth-24.jpg Energy to Earth • What day is this? A. B. C. D. • Spring Equinox Summer Solstice Fall Equinox Winter Solstice Seasons 5.53 min http://ccrc.unh.edu/~stm/AS/Common/Suns_Rays.JPG Solar Incidence of Angle • Light travels in a straight line • The curvature of the Earth forms the Incidence of Angle • The same amount of energy is spread over a larger area http://openlearn.open.ac.uk/file.php/2805/S250_3_002i.jpg Solar Radiation • Solar radiation – X-ray – blocked by atmosphere – Ultraviolet – mostly blocked by atmosphere – Visible – permeates, partially blocked by clouds – infrared – permeates http://mangalorean.com/circle/images/articles/20061130green4.jpg Albedo • Albedo is the fraction of solar energy reflected from the Earth back into space – a measure of the reflectivity of the earth's surface • Light soils, heavily vegetated areas have a high albedo • Dark soils, open areas have a low albedo • Ice, especially with snow on top of it, has a high albedo • Water is much more absorbent and less reflective, and has a low albedo http://media-2.web.britannica.com/eb-media/41/112541-004-926AB193.gif http://www.esr.org/outreach/glossary/albedo.gif Human Activity • All organisms change their environment – not just humans • Impact relating to lowering the albedo: – Pollution on ice and snow – Asphalt and cities – Clear cut or slash and burn http://www.mth.msu.edu/~ivanov/SatelliteP/Big/worldtradecenter_nyc800.jpg http://www.ncar.ucar.edu/assets/images/arctas_diagram.jpg Seasons and Sunlight • What is the solar angle of incidence for the equator for the globe on the left? A. 90° B. 66.5° C. 47° D. 43° • The globe on the left represents: A. Summer Solstice B. Winter Solstice C. Equinox and cannot tell if it is the spring or fall D. Not enough information http://www.physicalgeography.net/fundamentals/images/earth_sun_angles.gif Seasons and Sunlight • What is the solar angle of incidence for the equator for the globe on the right? A. 90° B. 66.5° C. 47° D. 43° • The globe on the right represents: A. Summer Solstice B. Winter Solstice C. Equinox and cannot tell if it is the spring or fall D. Not enough information http://www.physicalgeography.net/fundamentals/images/earth_sun_angles.gif Direction of Rotation • If you are looking down at the North Pole, does the earth spin A B A. Counterclockwise B. Clockwise http://www.flutrackers.com/forum/attachment.php?attachmentid=1512&d=1176083504 Eccentricity • 100,000 year cycle • Winter in North at Perihelion, and therefore shorter than summer • Low eccentricity of 0.005 • High eccentricity of 0.058 • Mean eccentricity of 0.028 • Present eccentricity 0.017 • Moving towards low centricity - warming Perihelion Aphelion http://en.wikipedia.org/wiki/File:Eccentricity_half.svg Obliquity • • • • • • Tilt of the Axis 41,000 year cycle Minimum tilt is 21.1º Maximum tilt is 24.5º Currently at 23.5º Tilt is decreasing cooling http://upload.wikimedia.org/wikipedia/commons/6/61/AxialTiltObliquity.png Precession • Wobble like a top • Completes the wobble every ~21,000 years • Other “north stars, Thuban in Draco and Vega in Lyra • Top 10 sec • Both 33 sec http://stardate.org/images/gallery/d_procession.jpg Milankovitch Cycles • These three cycles, in combination, can alter climate – Eccentricity – Obliquity – Precession • Milankovitch 2.38 min http://www.cgd.ucar.edu/research/highlights/section/milankovitch.jpg Questions?