Comets Asteroids and Meteorites Ch 9 Ch 8
- Slides: 53
Comets Asteroids and Meteorites Ch 9 Ch 8 and 9 HW posted and due Mon March. 14
COMETS AND THEIR COMPOSITION (Ch. 9 part II)
OUTLINE I. Nature of Comets II. Comets and the Origin of Earth’s Water III. Dust Composition VI. Summary (you need to take notes only on slides with blue titles)
Comet Hale-Bopp in 1997
I. Nature of Comets n Comets from the Greek “ ” (kometes). Long-haired ones. n Ancient greeks considered comets atmospheric phenomena, not part of the “perfect” heavens.
Question 1 n A comet is: A. A piece of interplanetary material that burns in the Earth’s atmosphere B. An object made of ices and dust in orbit around the Sun C. A shooting Star D. A rocky object that formed between Mars and Jupiter
I. Nature of Comets n Today we know comets are “dirty icebergs” in orbit around our Sun. n About ½ of a comet’s mass is water ice, the rest is cosmic dust and other ices. n Comet Orbits: generally very elliptical
I. Nature of Comets (Cont. ) n The nucleus is where all cometary activity originates. n When a comet is far from the Sun it is an inert object. n When a comet approaches the Sun the ices in the nucleus sublimate and create a cloud of gas and dust called the coma. n Sunlight and the solar wind push the dust and gas away from the sun creating the two tails.
Question 2 The tails of comets are always directly behind the nucleus. a) True b) False
Comet Hale-Bopp (Image by Elizabeth Warner on March 8, 1997) Ion Tail Dust Tail Coma
Comet Ikeya-Zhang (March 11 ‘ 02 images from Sky and Telescope)
DS 1 Spacecraft Image of Comet Borrelly in September 2001
Image of Comet Wild 2 from NASA's Stardust spacecraft. January 2, 2004
Deep Impact Spacecraft Image of Comet Tempel 1 in July 2005
Deep Impact Spacecraft Image of Comet Tempel 1 in July 2005
I. Nature of Comets (Cont. ) n Our solar system formed about 4. 6 billion years ago from the solar nebula. n The planets and Sun have been extensively processed since they formed. n However, comets have remained relatively pristine for the past 4. 6 billion years. n Why? • Comets are small and • stay far from the Sun most of the time.
Nature of Comets (Cont. ) n Two Known Sources of Comets • Oort Cloud (spherical shell ~ 50, 000 -100, 000 AU) • Kuiper Belt (disk ~ 30 -50 AU) (Astronomical Unit [AU] = Earth-Sun Distance) n Active comets do not last more than about 100, 000 years in the inner solar system because they lose material every time they pass near the Sun
Oort Cloud Sun • ~105 AU About 1/3 distance to nearest star
Kuiper Belt ~50 AU • Sun Neptune’s Orbit
Comets can come from the Oort Cloud and from the Kuiper belt Jovian planets protect Earth from most of bombardment Fig 9. 25
Outer Solar System
Outer Solar System
Collision in the Kuiper Belt Paiting by Daniel D. Durda
Comet SL 9 caused a string of violent impacts on Jupiter in 1994, reminding us that catastrophic collisions still happen. Tidal forces tore it apart during previous encounter with Jupiter
COMPOSITION OF COMET GAS Deuterium Abundance: • Why study it? • Chemical signature that can help us understand the possible links between comet water and Earth’s water
III. COMPOSITION (Cont. ) Deuterium Atom P N Hydrogen Atom P + + e - e
Normal and “Heavy” Water H 2 O HDO O H H D
COMPOSITION OF COMET GAS Deuterium Abundance: • The deuterium to hydrogen ratio has been measured in the water vapor in the coma of three comets: Halley, Hyakutake, and Hale. Bopp • These vales are plotted in the next slide
Deuterium/Hydrogen Ratios 10 -3 • HA • HB • HY 10 -4 Earth Oceans Solar Nebula 10 -5
D/H Ratios 10 -3 Comets 10 -4 • HA • HB • HY C Chondrites (H 2 O-rich meteorites) Cores of Molecular Clouds Earth Oceans Solar 10 -5 Nebula
III. COMPOSITION (Cont. ) n D/H Ratios in Comet Water: • Consistent with comets providing at least some of Earth’s H 2 O
IV. Comets and Origin of Earth’s Water n The contents of H 2 O in meteorites indicates a decrese in water abundance in the asteroid belt with decreasing heliocentric distance n Meteorites believed to have originated in the innermost part of the asteroid belt are the driest known material in the solar system n This suggests that the planetesimals formed in Earth’s zone should have had an even lower water content
Water contents of meteorites (which come from asteroids) Wet Dry
IV. Comets and Origin of Earth’s Water n Why is Earth rich in water and where did this water come from? n Comet impacts? n Asteroid impacts? n Probably both: The composition Earth’s water is consistent with a cometary origin of at least some of it. In addition, some asteroids can have as much as 15% water
V. COMPOSITION OF THE DUST n Cometary dust is approximately 50% silicates (minerals) and 50% organic solids (organic solids are made up of molecules with many carbon atoms). n If comets contributed a significant fraction of Earth’s H 2 O they probably also contributed significant quantities of organic molecules. n Hence, comets may have played a role in the origin of life on Earth. n However, there is no evidence that comets bring living organisms to Earth.
VI. SUMMARY n Comets are composed mainly of H 2 O ice plus cosmic dust and other ices n The main features of a comet are the nucleus, coma and tails n There are two known sources of comets: Oort Cloud and Kuiper Belt n The chemical composition of comets (rich in deuterium) is consistent with a cometary origin of at least some of Earth’s water and organic molecules
Asteroids and Meteorites Ch 9 part III
Asteroids and Meteorites Outline I. II. Introduction Asteroids • Orbits, sizes, composition III. Meteorites • • • Irons Stony-Irons Stones IV. Origin of Meteorites V. Meteorites and the Solar System VI. Summary
I. INTRODUCCION n Asteroids, comets and meteorites are the smallest members of the solar system n All these objects tell us much about how the rest of the solar sytem formed
II. ASTEROIDS n Most have orbits between Mars and Jupiter n Some have orbits that cross Earth’s, these are known as Earth-crossing asteroids n They have collided with Earth and they are likely to do so again. n The largest asteroid is Ceres
III. Types of Meteorites n Irons n Stony-Irons n Stones (~75% of all meteorites) Iron and stone Stone Differenciated Asteroid Non-differenciated Asteroid
III. Types of Meteorites n Irons n Stony-Irons n Stones (~75% of all meteorites)
Iron Meteorite
Stony-Iron
Stony Meteorite
III. Origin of Meteorites n Asteroids (more than 95%) • Asteroids collide with each other and breakup, some of those fragments become meteorites n Mars (a few percent) • Impacts on Mars kick martian material into space and some ends up falling on Earth n Moon (a few percent) • Also because of impacts
III. Types of Meteorites n Irons are excavated by collisions n Stony-Irons are excavated by collisions Iron and stone Stone Differenciated Asteroid Non-differenciated Asteroid
IV. Meteorites and the Solar System n Age of Solar System (4. 6 x 109 years) determined from radioactive dating of meteorites n Meteorites and Planets: • Information about asteroids, Mars, Moon. • Information about interior of Earth, e. g. , iron core.
V. Summary of Asteroids and Meteorites n Most asteroids orbit the Sun between Mars and Jupiter n Some asteroids cross Earth’s orbit and collide w/ Earth n Ceres is the largest asteroid n There are several types of asteroids n Meteorites are solid objects from space that reach the Earth’s surface n Most meteorites are from asteroids, a few are from Mars and the Moon. Most meteors are from comets n Three types of meteorites: Irons, Stony-irons, Stones n Meteorites tell us about the rest of the solar system.
- Name that space rock
- Difference between comets and asteroids and meteors
- Asteroids meteors and comets worksheet
- Comets asteroids
- An icy leftover planetesimal orbiting the sun is
- What is asteroid belt
- Origin of meteorites
- Iridium layer
- Asteroids
- An icy leftover planetesimal orbiting the sun is
- Jupiter nudges the asteroids through the influence of
- The pleiades myth
- Physical properties of comets
- Pink yellow green
- And because i am happy and dance and sing
- West side story romeo and juliet comparison
- Taller and younger shorter and older
- 5 centavos symbol
- Color red orange yellow green blue purple
- Your teacher is giving you a test worth 100 points
- Young and dyslexic igcse past paper
- What was the purpose of the sibley commission
- West yorkshire health and care partnership
- Whats a transverse wave
- Compare and contrast spring tides and neap tides.
- Is dependent variable x or y
- Linking helping and action verbs
- Category of life duties and responsibilities
- Types of records in hospital
- Transportation and assignment problems
- Compare and contrast cold wave and wind chill factor
- Final account format
- Siop and tap have similar descriptors and indicators
- Tomorrow creeps in this petty pace
- Credo the ritz carlton
- Automania definition 1950
- Vastus lateralis origin and insertion and action
- Two incidents involving automobiles great gatsby
- The giver chapter 3 and 4 questions and answers
- Narrative vs expository text
- Definition of compare/contrast
- Compare and contrast analog and digital forecasts
- Film the boy in the striped pyjamas
- I see said the blind man poem
- Hub and spoke system advantages and disadvantages
- Contrast signal words
- Input and output design in system analysis and design pdf
- The theme of the most dangerous game
- Simple subject
- And compound inequalities
- Soldering brazing welding
- Summer is like simile
- Parents and offspring
- Separation of powers and checks and balances