Class 9: Icy Moons and Space Junk
Today’s topics: Galilean moons: Io, Europa, Ganymede, Callisto Saturn’s moon: Titan Class Updates Reading: , 23.7 Homework 4 assigned, due next Monday Midterm next Monday, April 18th Midterm review material posted on website Class 9: Icy Moons and Space Junk Asteroids Meteor-stuff Comets
Moon Size Compariso n. Io Europa Ganymede Callisto Titan Triton Charon
Jovian Moons = Galilean Moons
Orbit Diameter Mass Density (days) (Moon = 1) (Moon=1)(g/cm 3 ) Io Europa Ganymede Callisto Jovian Moon Comparison
Exploration Galileo’s notes Voyager 1 Galileo spacecraft
Internal Structure
Tidal Heating
Io
Tides on Io
Plumes on Io: How?
Volcanism & Impact Craters on Io
Europa
Brittle Surface Ice Europa’s Subsurface Ocean? Liquid? Brittle Surface Ice Warm, Convecting Ice?
Evidence for Europa’s Subsurface Ocean
Europa’s Surface Features Ridges Spots Icebergs Craters Bright Bands
Ganymede
Ganymede’s Grooved Surface
Ganymede’s Magnetic Field: (Geologically Alive?)
Callisto
Callisto: Geologically Dead
Callisto’s Icy, Cratered Surface
How many? Saturn’s Moons most geologically dead cracks: Tethys, Mimas few craters: Enceladus TITAN?? New moon: S/2004S2 8/16/04 Cassini 48 total (15 major) km (Titan) inside/outside rings icy (small amounts of rock) How large? Where? Composition? Activity?
Titan
Titan’s Atmosphere
Probe descent: January 14, 2005 Huygens Probe Descent Titan
~10 km Huygens Probe on Titan Landing site
Titan’s Surface
Asteroids Ida Gaspra Mathilde
Asteroid Locations
NEAs This Week Size > 1 km = globally destructive
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
Upcoming Mission: DAWN Ceres Vesta
Meteor-stuff
Peekskill, NY August 1992 Incoming Debris
Definitions
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
Comet Tails
Comet Tails & the Sun
Where do comets originate? (I) Sedna Halley’s Comet
Where do comets originate? (II) Comet Hyakatuke Comet Hale Bopp
Comet Shoemaker-Levy 9