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The Solar System. CHAPTER 15 Vagabonds of the Solar System Asteroids and Comets. Titius – Bode Law. Asteroid Belt. Asteroids. Orbit of Uranus fits the Titius -Bode Law. 1800—Baron Xavier von Zach organizes the “ Himmelspolizei ” to find 2.8 AU planet.
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The Solar System CHAPTER 15 Vagabonds of the Solar System Asteroids and Comets
Titius – Bode Law Asteroid Belt
Asteroids Orbit of Uranus fits the Titius-Bode Law 1800—Baron Xavier von Zach organizes the “Himmelspolizei” to find 2.8 AU planet 1/1/1801—Giuseppi Piazzi discovers the 1st asteroid—Ceres Four largest asteroids, Ceres, Vesta, Pallas, Hygieamake up 1/2 the mass of the belt.
Lagrange Points: L1–L5 • 3 Forces: • Gravitational • Centrifugal • Coriolis • ‘Equipotential’ contours • Gradients: • Away • Toward • Only L4 and L5 are ‘stable’
‘Greeks’ ‘Trojans’
Question The Lagrange points (L4 and L5) in the Jupiter-Sun planetary system are _____. positions in space at Jupiter's orbital distance from the Sun, where the combined forces of the Sun and Jupiter trap asteroids, called Trojans (and Greeks). points at high latitudes on Jupiter where auroras (called Lagrangian auroras) occur most frequently. areas in the asteroid belt where gravitational interaction of Jupiter with asteroids disturbs their orbits and causes a Kirkwood Gap. locations that would make excellent repositories for Earthling’s nuclear waste according to the French physicist, Joseph Louis de’Lagrange. positions from which space probes to the outer solar system are launched.
Asteroids Outside the Belt Notice ‘NEO’s’
Gaspra First asteroid to be imaged— by Galileo spacecraft(1991)
Question A piece of rock from outer space that reaches the Earth's surface after surviving a fiery passage through the Earth's atmosphere is known as a ____. Meteoroid Hemorrhoid Meteorite Deltoid Sigmoid
Iron Meteorite Surface covered w/depressions caused by ablation
Iron Meteorite • Cut & polished • Etched w/acid • Reveals ‘Widmanstätten’ pattern • Pattern forms as molten metal cools slowly over millions of years
Allende Meteorite • Chihuahua, Mexico 1969 • 4.56 billion yrs old • Carbonaceous chondrite • Contains Mg26
Question The Allende meteorite contained a large abundance of 26Mg, an isotope of magnesium. What is the significance of this? Aliens had visited our solar system in the remote past leaving behind large amounts of radioactive 26Mg, a by-product of nuclear fusion propulsion systems. Magnesium has a high melting point, so Allende was a piece of asteroid that must have formed in the inner part of the solar system. The 26Mg in Allende probably became radioactive when it landed near a nuclear reactor in Chihuahua, Mexico. 26Mg is the stable product of the decay of radioactive 26Al. The 26Al parent of 26Mg was probably produced in a nearby supernova explosion whose shock wave might have triggered the formation of our solar system. This discovery suggests that elements such as 26Mg were more abundant in the early Kuiper Belt than we had originally thought.
Barringer(Meteor) Crater 1.2 km Impact ~ 50,000 Ya by 50 m iron meteorite travelling at 13 km/s. Energy yield ~ 20 Mtons
Artist’s Impression of The Tunguska Event 15 km from Ground Zero—A few minutes after explosion 50 km South of Ground Zero • A 100 kiloton stony asteroid(or comet) entered atmosphere travelling at 22 km/s, or 50,000 mph! • It exploded above Ground Zero , releasing about 300 Hiroshima A-bomb equivalents—or 5 Megatons of TNT!
Leonid Kulik’s Photograph —1927 No crater! At ground zero — an 8 km zone of trees scorched and devoid of branches, but standing upright. Those farther away had been partly scorched and knocked down in a direction away from the center. Area of leveled forest ~2,150 square kilometers!
A Doomsday Scenario It would soon prove to be a day unlike any other for the dinosaurs and other species that roamed the Earth 65 million years ago. A tiny bright point of light not unlike that of a bright star suddenly appeared in the daytime sky. The bright spot was a 10-km wide asteroid headed towards a point in Earth’s orbit where unfortunately it would arrive at the same time as the Earth! Upon entering the atmosphere, observers would have only 10 seconds left to live before it struck the ground. The explosion caused by the impact released an energy equivalent to that of a 100 million megaton thermonuclear blast—equivalent to 100,000 times the explosive energy store in the combined U.S.—Russia nuclear arsenal!
KT Mass Extinction • Temperatures soared to over a million degrees K — completely vaporizing everything within hundreds of kilometers. • A huge fireball exploded out of the sea and spread outward faster than the speed of sound leaving death and destruction in its wake. • The shock it generated left a crater 200 km wide. • Earth’s Cretaceous period had ended abruptly! The Tertiary period had begun!
KT Event • 10 km asteroid @ 22 km/sec • 100 million megatons TNT • 50 MT Largest man-made • 1000 MT combined US-Soviet arsenal
Evidence ─ First Hint • Walter discovered a distinct sequence of rock layers marking the 65 million year old boundary between the Cretaceous and Tertiary periods—the ‘KT’ boundary ─ made up of : • a lower layer of sedimentary rock rich with a wide variety of marine fossils • a centimeter-thick layer of clay stone devoid of all fossils • an upper layer of sedimentary rock containing a much reduced variety of marine fossils • The K comes from Kreidezeit, the German word for Cretaceous. Walter & Luis Alvarez at Gubbio, Umbria, Italy
Iridium Concentration The ‘thin’ clay layer is devoid of fossils … and rich in the element Iridium!
Chicxulub Crater—Yucatan Landsat radar image
Energy Released by Impact Russian Impact ~300 Ktons —Feb 15, 2013 A Tunguska Event takes place every several hundred or a thousand yrs ─ takes out New York! Every 100,000 yrs an impact of 8000 megatons causes a nuclear winter! Every 10’s of million years a >2-km global impactor hits releasing a million megatons!
Probability of Death… 1 in 195,249,054 Odds of Winning Powerball
Includes the infamous asteroid, 1997XF11, which made a major impact on the world's headlines in March 1997 when observations indicated that it had a good chance of colliding with the Earth in 2028! NEO’s An up to date map of the inner solar system displaying the orbits of the terrestrial planets and the estimated position of thousands of known asteroids. This diagram is missing comets, space probes and the undiscovered asteroids. It is estimated that there are perhaps 100,000 to 1,000,000 undiscovered asteroids on similar Earth crossing orbits. Have a Nice Day!
Question What is the likely connection between the metal iridium and the demise of the Earth's dinosaur population? Iridium, which is found in abundance on Earth's surface, is poisonous to reptiles. Radioactive iridium is found beneath Earth's crust. Meteor impacts during the dinosaur age probably exposed and uncovered enough of it to poison the dinosaurs. Iridium is highly radioactive. Its presence in a geologic layer dating to the dinosaur age suggests that natural radioactivity reached dangerous levels at that time, and the dinosaurs died from overexposure. Iridium is found in meteorites but is rare on the Earth. The existence of a world-wide layer of it suggests a large meteor impact during the dinosaur age. This impact probably triggered global volcanism, raised enough dust to block out sunlight and caused other catastrophes that killed the dinosaurs.
Structure of a Comet • Dust tail blown by solar wind • Ion tail blown by solar radiation (sunlight)
Halley’s Comet Image by ESA Giotto flyby in 1986
Comet Tempei 1 • Image by Deep Impact Spacecraft in 2005 • Launched projectile into comet at 37,000 km/hr • Low density (0.6 g/cm3) ‘rubble pile’
