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Asteroids Ida Gaspra Mathilde
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Class 22: Space Junk (I)
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Class 22: Space Junk (I)
Today’s topics: • Asteroids• Meteor-stuff• Comets
Class Updates• Reading: 23.10• Lecture schedule update• Homework & Exams returned
Asteroids
Ida
Gaspra
Mathilde
Asteroid Locations
NEAs This Week
http://neo.jpl.nasa.gov/ca/
A Bad Day…. 65 Million Years Ago
Chicxulub
Asteroid Shapes & Sizes
Mars
Asteroid Distances
Mini Moons of Asteroids
small moon (1.5 km)
Ida (100 km)
Asteroid Mission: NEAR
Eros gravity
close-upimage
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Eros Up Close
Upcoming Mission: DAWNQuickTime™ and a
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Ceres
Vesta
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Meteor-stuff
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Peekskill, NYAugust 1992
Incoming Debris
Definitions
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.
a. Cometb. Meteoroidc. Meteord. Meteorite
Which of these is the proper scientificname of your discovery?
Challenge Question
Meteor Showers
Leonids, 11/2001 Perseids, 8/2004
Earth’s largest meteorite….thus far
Hoba MeteoriteNamibia 66-110 tons
Moon
(meteor showers only)
Mars
Asteroid Vesta
Origins & Ages of Meteors
• Stony-Iron (2% falls, 8% finds)– asteroid core/mantle?
Compositions
(glassy beads, grains)(carbon, volatiles)
• Stones (92% falls, 26% finds)– rocky material (silicates)– ancient solar system – Carbonaceous chondrites
• Irons (6% falls, 66% finds)– like Earth core (melting)– debris asteroid core?
Bill Cassidy
Where are meteorites found?
MeteorCrater
Northern Arizona
Wolfe Creek, AustraliaManicouagan, Quebec, Canada
Clearwater Lakes, Quebec, Canada Gosses Bluff, Nor. Territory, Australia
More Terrestrial Craters
Donahue meteorite Peekskil Chevy
• 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
Hits & Misses
Comets
May 7, 2004
Anatomy of a Comet
Head
Tail
GasTail
Comet West
nucleusNucleus:Comet Head
nucleus surface
coma
Nucleus: Comet Wild 2
Comet Tails
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Sunlight = Tails (movie)
Where does gas tail point?
Where do comets originate? (I)
SednaHalley’s Comet
Where do comets originate? (II)
Comet Hyakatuke
Comet Hale Bopp
Comet Shoemaker-Levy 9
12
3
Which is which?
a. (1) comet; (2) meteor; (3) cometb. (1) asteroid; (2) meteor; (3) cometc. (1) comet; (2) asteroid; (3) meteord. (1) meteor; (2) asteroid; (3) comet
Review
On the morning of June 20, 1908 witnesses described a On the morning of June 20, 1908 witnesses described a brilliant brilliant
fireball, brighter than the Sun, streak across the sky. Still fireball, brighter than the Sun, streak across the sky. Still de-de-
scending, it exploded with a blinding flash & an intense scending, it exploded with a blinding flash & an intense pulse ofpulse of
heat. The blast was heard up to 1000 km away; the heat. The blast was heard up to 1000 km away; the resultingresulting
pulse of air pressure circled Earth twice. 1000s of tons of apulse of air pressure circled Earth twice. 1000s of tons of apowdery material resembling powdery material resembling carbonaceouscarbonaceous chondriteschondrites
were laterwere laterfound scattered in the soil. found scattered in the soil.
What do you think was the likely source of the Tunguska
event?
Trees flattened out to 30 km
Tunguska, RussiaChallenge Question