Impacts from Above 50,000 yr old Meteor Crater, AZ Watching the skies for potential catastrophes Mass Extinctions: Death and Destruction
Five Big Mass Extinctions When (End of ) ~440 Myrs Ordovician ~360 Myrs Devonian 251 Myrs Permian 205 Myrs Triassic 65 Myrs Cretaceous *Went extinct, **From Jablonski (1991,1995) Species Major Loses to Loss** 85 ±3% Brachiopods & bryozoans 83 ± 4% Rugose & tabulate corals, armored* & jawless fish 95 ± 2% All life! - Trilobites*, corals*, blastoids* 80 ± 4% Most synapsids 76 ± 5% Dinosaurs, marine reptiles, ammonites* Causes of Mass Extinctions Major and rapid environmental change - to fast for species to adapt Such as: Meteorite impacts Massive global eruptions Rapid climate change Major sea level fluctuations Nearby supernova event Ultimate Natural Disasters
Case Study in End Times: K-T Extinction 65 Million yrs ago 10 km rocky object Evidence Iridium Shocked Quartz
The Impact Site 180 km What Happened? Immediate Area 1. Tsunami & Fallout 2. Total destruction Global Effects 1. Darkness - decrease in photosynthesis 2. Cold (2-3 Months of -20 C) 3. Followed by Greenhouse warming 4. Acid Rain 5. Wildfires 6. Toxic Seawater
More Recently, 1994: Comet Shoemaker-Levy At least 21 fragments (2km) Large Impacts What is out there - what could hit us? What types of things hit us? What happens when they hit us? What do we do to prepare? How do we watch for potential objects? What do we do if we see one?
Planets (1) A "planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit. Dwarf Planets Pluto Ceres Eris Pluto and Charon A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighborhood around its orbit, and (d) is not a satellite.
Largest Dwarf 2003UB313 Discovered July 2005 97 AU 1-1.5x size of Pluto? Eris Small Solar System Objects: Asteroids and Comets, Meteoroids, Interplanetary Dust 10 micron dust particle Toutatis (3) All other objects except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies".
Fate of Small Bodies Collision with the Sun Collision with a Planet Capture by a Planet Fragmentation Ejection from the Solar System Preservation Fate of Small Bodies Collision with the Sun Collision with a Planet Capture by a Planet Fragmentation Ejection from the Solar System Preservation Phobos Deimos Gaspra
Fate of Small Bodies Collision with the Sun Collision with a Planet Capture by a Planet Fragmentation Ejection from the Solar System Preservation Source of Meteorites Fate of Small Bodies Collision with the Sun Collision with a Planet Capture by a Planet Fragmentation Ejection from the Solar System Oort Cloud Preservation Earth Jupiter
Oort Cloud Jan Hendrick Oort Fate of Small Bodies Collision with the Sun Collision with a Planet Capture by a Planet Fragmentation Ejection from the Solar System Preservation Main Asteroid Belt Kuiper Belt Earth Jupiter
Our Main Threat: Asteroids & Comets 250 m elevation NEAR Spacecraft Eros
Major Asteroid Groups Near Earth Asteroids < 1 AU-2 AU Earth crossing Orbit Main Belt 2-4 AU Between Mars and Jupiter Centaurs 5.2-25 AU Outer Solar System AU = Astronomical Unit (Distance from Sun to Earth) Main Asteroid Belt Mathilde & Eros (NEAR)
Kleopatra Gaspera Ida and it s moon Dactyl (Galileo) Near Earth Asteroids Itokawa 600m Hayabusa
Near Earth Asteroids (NEA s): As of November 24, 27, 2008: 2009: 5865 6694 NEA s are known (almost (again almost 1000 more 1000 than more 1 than year 1 ago) year ago) 997 1079 are are currently classified as as Potentially Hazardous Asteroids (PHAs) Near Earth Asteroids (NEA s):
Comets Icy Objects from the outer solar system Comet McNaught (January 2007) Nucleus of Comet Wild 2 Comets = Perturbed Kuiper Belt and Oort Cloud Objects
Comet Temple-1 Deep Impact
Comets come from: Kuiper Belt (& Oort Cloud) Gerald Kuiper Comet Hale-Bopp Meteor Showers 1833 England Leonid Meteor Shower
Meteorites Peekskill (NY) Fall, Oct. 9, 1992 Terminology Meteoroid Meteor & Meteor Shower Fall & Finds Meteorite Meteorite Finds: Antarctica
Types of Meteorites (Falls) Stones Carbonaceous Chondrites Ordinary Chondrites 5% 86% Achondrites 9% Irons 4% Stony-Irons 1% Chondrite
Chondrules under a scope X-Ray Image Chondrites Ordinary Carbonaceous
Achondrite - Stony Meterorite A stone from the Stannern eucrite shower that fell over Moravia, Czech Republic in 1808. Achondrites: Eucrites
Iron Meteorite Structure in Iron Meteorite
Hoba Meteorite Iron 55,000 kg Namibia (1920) ~88,000 yrs old 15.5 tons Largest in the US iron Willamette Valley Meteorite
Stony-Iron: Palasite Olivine Iron Meteorite Features: Fusion Crust & Magnetic Attraction Carbonaceous Chondrite - Nevada
Meteorite Features: Smooth Surface w/ Thumb Prints Source of Meteorites Irons Stony-Irons
Meteorite Impacts Crater Formation
Central Peak Ejecta Blanket
Ray Formation Tycho
Large impacts can eject material into space Lunar Meteorites
Martian Meteorites - SNC s Crater Types Simple Crater - Meteor Crater, AZ Crater Chains - Moon Complex Crater - Tycho Crater, Moon
Crater Types (cont.) Multiring Crater - Orientale Basin (Moon) Some Earth Craters (Shuttle Images) Chad, 17 km Several 100 Myrs ago Namibia, 2.5 km 5 Myrs ago
Manicouagan Crater, Quebec 214 Myr ago 70 km crater What was the largest impact in the United States in the last 100 Myr? Chesapeake Bay 35 Myr ago 3-5 km object
Another big one Manson, Iowa 74 Myr ago 3 km object Not all hit the Ground - Fireballs (Airbursts)
Tunguska, 1908 50-60 m stony meteorite 400Km - Hartmann