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Class 22: Space Junk (I). Class 22: Space Junk (I). Class Updates • Reading: 23.10 • Lecture schedule update • Homework & Exams returned. Today’s topics: • Asteroids • Meteor-stuff • Comets. Asteroids. Ida. Mathilde. Gaspra. Asteroid Locations. NEAs This Week.
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Class 22: Space Junk (I) Class Updates • Reading: 23.10 • Lecture schedule update • Homework & Exams returned Today’s topics: • Asteroids • Meteor-stuff • Comets
Asteroids Ida Mathilde Gaspra
NEAs This Week http://neo.jpl.nasa.gov/ca/
Chicxulub A Bad Day…. 65 Million Years Ago
Mini Moons of Asteroids small moon (1.5 km) Ida (100 km)
Eros gravity Asteroid Mission: NEAR close-up image
Upcoming Mission: DAWN Vesta Ceres
Incoming Debris Peekskill, NY August 1992
Challenge Question Suppose that you are hiking along the icy banks of an Antarctic glacier and you stumble upon a very odd looking rock, which you later confirm to be a chunk of an asteroid that fell to Earth. Which of these is the proper scientific name of your discovery? Comet Meteoroid Meteor Meteorite
Meteor Showers Leonids, 11/2001 Perseids, 8/2004
Earth’s largest meteorite….thus far Namibia 66-110 tons Hoba Meteorite
Asteroid Vesta Mars Moon (meteor showers only) Origins & Ages of Meteors
• Irons (6% falls, 66% finds) • like Earth core (melting) • debris asteroid core? • • Stones (92% falls, 26% finds) • rocky material (silicates) • ancient solar system • Carbonaceous chondrites • • Stony-Iron (2% falls, 8% finds) • asteroid core/mantle? Compositions (carbon, volatiles) (glassy beads, grains)
Where are meteorites found? Bill Cassidy
Meteor Crater Northern Arizona
More Terrestrial Craters Wolfe Creek, Australia Manicouagan, Quebec, Canada Gosses Bluff, Nor. Territory, Australia Clearwater Lakes, Quebec, Canada
Hits & Misses • Human strike: Annie Hodges; Sylacauga, AL; bruised; 11/30/54 • Animal strike: Dog; Nakhla, Egypt; 6/24/11 • Structures: Donahue home; Wethersfield, CT; 11/8/82 Chevrolet; Peekskil, NY; 8/9/92 Donahue meteorite Peekskil Chevy
Comets May 7, 2004
Gas Tail Tail Head Comet West Anatomy of a Comet
Nucleus: nucleus nucleus surface coma Comet Head
Where do comets originate? (I) Halley’s Comet Sedna
Comet Hyakatuke Comet Hale Bopp Where do comets originate? (II)
Review Which is which? 2 1 3 (1) comet; (2) meteor; (3) comet (1) asteroid; (2) meteor; (3) comet (1) comet; (2) asteroid; (3) meteor (1) meteor; (2) asteroid; (3) comet
Challenge Question Tunguska, Russia On the morning of June 20, 1908 witnesses described a brilliant fireball, brighter than the Sun, streak across the sky. Still de- scending, it exploded with a blinding flash & an intense pulse of heat. The blast was heard up to 1000 km away; the resulting pulse of air pressure circled Earth twice. 1000s of tons of a powdery material resembling carbonaceouschondrites were later found scattered in the soil. What do you think was the likely source of the Tunguska event? Trees flattened out to 30 km