Class 22: Space Junk (I)

Today’s topics: Asteroids Meteor-stuff Comets Class Updates Reading: Lecture schedule update Homework & Exams returned

Asteroids Ida Gaspra Mathilde

Asteroid Locations

NEAs This Week

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-up image

Eros Up Close

Upcoming Mission: DAWN Ceres Vesta

Meteor-stuff

Peekskill, NY August 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.Comet b.Meteoroid c.Meteor d.Meteorite Which of these is the proper scientific name of your discovery? Challenge Question

Meteor Showers Leonids, 11/2001Perseids, 8/2004

Earth’s largest meteorite….thus far Hoba Meteorite Namibia 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?

Meteor Crater Northern Arizona

Wolfe Creek, Australia Manicouagan, 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 Gas Tail Comet West

nucleus Nucleus: Comet Head nucleus surface coma

Nucleus: Comet Wild 2

Comet Tails

Sunlight = Tails (movie)

Where does gas tail point?

Where do comets originate? (I) Sedna Halley’s Comet

Where do comets originate? (II) Comet Hyakatuke Comet Hale Bopp

Comet Shoemaker-Levy 9

1 2 3 Which is which? a. (1) comet; (2) meteor; (3) comet b. (1) asteroid; (2) meteor; (3) comet c. (1) comet; (2) asteroid; (3) meteor d. (1) meteor; (2) asteroid; (3) comet Review

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 carbonaceous chondrites 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 Tunguska, Russia Challenge Question