Meteors

Ground Zero 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.

Shooting Stars Objects in space move very quickly compared to Earth. Any object entering the earth’s atmosphere from space will heat up and glow. These bright objects streak across the sky as meteors. atmosphere earth meteor

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

Types of Meteorites Meteors match the types of material in comets (95%) and asteroids (5%). –Comets mainly ice - few reach ground –Asteroids mainly rock - makes most 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. –Earth’s surface about 500 million square km –1 meteorite per 1 square km every 50,000 years The surface of the Earth hides most meteorites. –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 Meteorites can be matched to planetary surfaces. –Spectral analysis –Matches to Moon, Mars, asteroids These meteorites were blasted from their parent planet. Meteorite from the asteroid Vesta

Jupiter Impact Comet Shoemaker-Levy 9 struck Jupiter in –Broke up before impact. –Pieces damaged 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. –180 km crater –12 km object –Debris blocked sunlight –Plants and animals went extinct