Impact What is the chance of being near (within 1 km) a meteor as it strikes the ground during your lifetime? A. About 1 in a thousand. B. About the same as winning the lottery. C. About the same as winning the Nobel Prize in physics. D. Virtually impossible.

Meteorites Some meteors do not entirely burn up. Outer layers of a meteor can protect the core, then the atmosphere slows it down. The remaining rock that reaches earth is a meteorite. earth meteor earth meteorite

Types of Meteorites Meteorites match the types of material in comets (95%) and asteroids (5%). Since comets are mainly ices, few of these reach ground. Asteroid material makes up almost all of the meteorites. Carbon chondrites: 4 %Stony meteorites: 88 %Metallic meteorites: 8 %

Finding Meteorites About 10 to 50 meteorites land each day, or about 10,000 meteorites land per year. The surface of the earth is about 500 million square km. Each square km of the earth gets one every 50,000 years. 2/3 of the meteorites land in the ocean. 1/4 of those on land are in desolate areas (deserts, poles) Antarctica is a good place for meteorite hunting.

Planet Parts Spectral analysis of planetary surface allow matching some stony metorites to specific planets. These meteorites were blasted from their parent planet. Matches have been made to the Moon, Mars and other minor planets. Meteorite from the asteroid Vesta

Jupiter Impact Comet Shoemaker-Levy 9 Impact in 1994 Comet broke up before impact. Each piece left major damage to Jupiter’s atmosphere.

Earth Impact Meteor Crater, Arizona Impact 50,000 years ago Object 40 meters in diameter Iron composition Tunguska, Siberia, Russia Impact June 30, 1908 Object 60 meters in diameter Stony composition

Extinction An object the size of Shoemaker-Levy 9 collided with the earth 65 million years ago. This collision ejected so much debris that the sun was blocked, and there was extinction. The crater is about 180 km across, caused by a 12 km object.