Class Note for PTYS 206 with Professor Yelle at UA 2
Class Note for PTYS 206 with Professor Yelle at UA 2
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Date Created: 02/06/15
GIANT IMPACTS Fiction and Fact Starting with Fiction Why Science Fiction is just thatFiction in a AWquot r liLIF39E39iL Ji 7 n Deep Impact 1998 Written by Bruce Joel Rubin and Michael Tolkin BRAINSTORM 1 Come up with a few examples of bad science in the film Why do you think each example is a problem 39 Why do you think the lmmakers I included that scene fact etc A Very Few Examples Initial trajectory of impactor cannot be determined from one observation Most cars don t just blow up when they roll Despite movie evidence to the contrary sound cannot travel through space thus there would be no sound from the comet A Few More The tail of a comet is made up of SMALL dust particles and gasnot of ship damaging sized rocks Though the small particles can move fast enough to cause signi cant problems Thermal inertia is ignored on the comet Confusion about space communications The Earth is struck by meteors all the time Problem Meteors are de ned as the bright streak of light in the sky caused by an object burning as it moves through the atmosphere It CANNOT strike anything METEORITES strike the planet We are approaching perigee Problem Perigee is the closest distance an object orbiting Earth will get to the planet Neither the comet nor the spacecraft was orbiting anything so it cannot be at peri whateverlet alone perigee 39 On to the r lots Impacts are a fact of life They happen and some have had a huge effect on the planet BRAINSTORM 2 What evidence do we have that impacts are common in the solar system Is all of that evidence apparent on Earth why What are the impactors In Deep Impact a large comet was on a collision course with Earth Brainstorm 3 Asige from comets what sorts of things cank b e impactors L Tons of material falls to Earth regularly Impactors include Dust particles Fragments of asteroids and planets broken off during collisions Larger bodies thrown out of their orbits by gravity Gianquot impacts Giant impacts are a impacts with larger bodies usually de ned as greater than 1 km in diameter Giant impacts have occurred on all of the solar system bodies and are a necessary consequence of solar system formation and gravity iungusli On the morning ofJune 301908 a tremendous explosion occurred in a remote area of central Siberia nearthe Tunguska river Seismic vibrations were recorded by sensitive instruments as much as 1000 km away At 500 km observers reported quotdeafening bangsquot and a fiery cloud on the horizon About 170 km from the explosion the object was seen in the cloudless daytime sky as a brilliant sunlike fireball At distances around 60 km people were thrown to the ground or even knocked unconscious windows were broken and crockery knocked off shelves Reindeer herders asleep in their tents in several camps about 30 km from the site They were blown into the air and knocked unconscious More Damage from T LIrJgL ska GEOLOGIC TIME SEAL P pERIQADM EPOCH u JUVGASS CA A A C rsf 51rd v 39 Thassic German H y 52339 Pennsywaman Mssiss ppiun lambseh ars r fawn Fciss s Geological Evidence of the lmpaci o The boundary between the Cretaceous and Tertiary Periods KT Boundary K for kreide the German word for limestone is determined by depth in rock formations 0 At the depth of the KT boundary there is a dark streak between the rocks of each period This dark streak can be found at the KT boundary around the world 0 This dark streak contains iridium an element that is rare on the surface of the Earth Having the element present at the same depth around the globe implies a worldeffecting event at that time A GIANT IMPACT This is the Iridium bearing layer The Chicxulub Crater This radar image off the Yucatan peninsula shows an interesting circular pattern This VERY LARGE structure of concentric rings is what would be expected for an impact large enough to spread iridium around the world and kill the dinosaurs This is thought to be the impact location of the K T boundary collision Consequences of Giant mpacts Brainstorm 4 What could be the effects of a giant impact on Earth s environment Environmental Effects Include 1 The shock of the impact produced magnitude1O earthquakes which were greater than the magnitude of any we have measured in modern times 2 Wild fires caused by falling impact ejecta were generated around the globe 3 Huge amounts of dust were injected into the atmosphere This perhaps was the most serious effect globally as it reduced the amount of sunlight reaching the Earth s surface for many months 4 Acid rain and other toxic substances precipitated out of the atmosphere for years following the event IABLE 3 Chances o lylng from selecled causes USA Cause a deem Motor vehme acmdam Murder Fire Firearms accldenl Astemldcnmet Impact lower Ilmll Flectvoculmn ASTEROlDCOMEI IMPACT Passenger aircraft crash Hood Tovnado Venomous bite or slung AstaloIdcumel Impact upper Ilmlt Frraworks accident Food pmsnmng by bmuhsm Drmklng water wu39n EPA hum u TCE Chances 1 In 100 1 In 300 1 m 800 1 n 2500 1 In 3000 1 In 5000 1 In 20000 1 m 20000 1 in 30000 1 in 60000 1 In 100000 1 In 250000 1 In 1 When 1 m 3 mHhon 1m 10 mmwon EPA Enwrunmemal Protection Agency TCE luchlomemylene Any Bene t to mpacts Brainstorm 5 What could impacts have done to help the development of Earth both geological and biological s include 0A heat source for early Earth 0 Potentially a source of water and biological material for early Earth 0 Shake up the food chain allowing different organisms to thrive The K T impact killed of 75 of species This left room for the other 25 to expand grow and evolve If it weren t for Chicxulub we might not be here toda
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