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Impact Craters Leave an Impression… Craters are everywhere! Andy Saulietis LPL / UA The Moon Apollo 17 NASA Mercury Asteroids NASA NASA/GSFC Mars NASA NASA Meteor Crater, AZ USGS Geoffrey Notkin Even Earth… So what causes craters? •Left over building blocks of the solar system (~5 billion years old) •Vary in size, from a few feet to a few miles •Millions of potential meteors in our solar system alone •Travel in excess of 20,000 mph NASA Asteroids and Comets! When these objects collide with another body, like the Earth, the result is a crater. •Size: 150 Feet Across1 •Composition: NickelIron1 Wright, S.P •Speed: 28,600 MPH1 •Age: 50,000 years old1 •Energy: 2.5 Megatons1 Meteor Crater, AZ 1Barringer Meteor Crater Site http://www.barringercrater.com/ Shoemaker-Levy 9 NASA/GSFC Why do some planets have more craters than others? •Atmosphere •Oceans •Plate Tectonics •Location NASA/GSFC So why do we care? NASA/GSFC Extinction Extinction •Estimated that there have been at least 5 mass-extinctions in Earth’s history1 •Up to 90% of all species killed off2 •At least one is believed to have been caused by a meteorite1 •65 Million Years ago, Yucatan Penninsula2 •>100 Miles across2 •Force Greater than 1,000,000 megatons3 1 Lee Siegel, space.com 2 NASA/GSFC 3 Arnett, Bill, UA
