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Asteroids, Meteors, Comets
Solar System Debris
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Meteors Meteorthe bright
streak of light that is
produced when apiece of debris burns
in earths atmosphere
Meteoroidthe piece
of debris (usually
smaller than 1 cm)
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Meteorites Meteoroids strike earths
atmosphere going
20-160 thousand mph
Burn in atmosphere between 60 50 milesabove ground
If debris is large enoughand doesnt all burn, the
piece that strikes theground is the Meteorite
To findlook in desert orin Antarctica
Not usually very large,butoccasionally we getbigger ones.
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Why Meteor Showers OccurEarth orbits through a trail of debris
(usually left behind by comet or other parent)
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Meteor ShowersShower Name Date of Max Parent ObjectQuadrantids Jan. 3
Lyrids Apr. 22 Comet Thatcher
Eta Aquarids May 4
Delta Aquarids July 29
Perseids Aug. 12 Comet Swift-
TuttleOrionids Oct. 21 Comet Halley
Leonids Nov. 16 CometTempel-Tuttle
Geminids Dec. 13 Asteroid Phaethon
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Types of Meteorites Stony meteorites94% of all that fall to Earth(most are chondritesnamed for chondrules ofglassy silicates inside)
Iron meteorites5% of meteorites that fall to Earth(nearly pure iron and nickel)
Stony-iron meteorites1% that fall to earth
Age of meteorites is about 4.5 billion yrs. oldleft
over from solar system formation Parent bodiesasteroids
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The Possible Evolution of a Parent
Body of Meteorites
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What happens if a REALLY big meteorite makes it
through the atmosphere and hits a planet?
Meteor Crater (Winslow, AR)
Crater is almost 1 mile acrossproduced by a meteorite that
was ~150 ft. in diameter
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So what would happen if.Impact Diameter (m) Yield (megatons) Interval (yrs. Consequences
~10 m
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Q:When did this happen?
A: about 50,000 yrs. ago
Meteor Crater (Winslow, AR)
Whens the next one? um, we dont know
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Asteroids Asteroidsmetallic, rocky bodies
without atmospheres that orbit theSun but are too small to beclassified as planets.
How many are there? We now know orbits of
50,000but we dont know themall
Most are found in asteroid beltbetween Mars and Jupiter
(2.1-3.3 AU)
Lots of space in between themits not like StarWarstheyreabout 5 million km apart
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Asteroid Locations
7000 asteroids in1997 (not to scale)
Trojan
asteroids
Trojan
asteroidsJupiter
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Do Asteroids come near Earth? Amor Asteroidspass inside Mars orbit but dont cross
Earths
Aten asteroidscross Earths path when furthest from sun Apollo asteroidsEarth crossing asteroids (largest known is
~8km in diameter)
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The Size of Near-EarthAsteroids
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What are the largest asteroids?
Ceres (now classified as a dwarf planet likePluto) is 1000 km in diameter (see image)
Pallas and Vesta are both ~500 km in
diameter
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The asteroid Toutatis has
dimensions of2.9 x 1.5 x 1.2 miles
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951 Gaspradimensions of
18.210.58.9 km
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433 Erosdimensions of
13 13 33 km
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Near Earth Asteroid Rendezvous
(NEAR) mission visited andlanded on Eros in 2000
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The Chicxulub
Impact Structure
100-150 mile diameter crater off
Yucatan Peninsula dating back to
65 millions years ago
So what? This is the same time as
dinosaur fossils; in layers of
sediment, theres a concentration of
iridium worldwide from a settling
of a worldwide dust
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Comets Dirty Snowball
made of ice (frozen
water, CO2, CO,formaldehyde),dust,
rock
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The Parts of a Comet
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The Orientation of
Comet Tails
Tail always points awayfrom the sunso it can
lead the comet (like at
the right of the diagram)
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Comet Halle-Bopp in 1997
(nucleus of 40 km)
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Comet Hyakutake in 1996
(nucleus of 2 km)
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Halleys comet in 1986
(nucleus of 15 km)
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The Oort Cloud
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Stellar Perturbations
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Kuiper Belt Comets
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Comet Shoemaker-Levy 9
(impacted in 1994) 1994 string of a
comets broken apart
fragments labeled AthroughW heading
straight toward Jupiter
real time impact
witnessed during our
lifetime
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What it would have looked like
on Earth compared to Jupiter
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1. Graph radius of crater (y-axis) vs.height of drop (x-axis).
Remember to make your graphwith labels, units, and evenly
marked out intervals.
2. Graph radius of crater (y-axis) vs. mass of sphere (x-axis).
Remember to make your graphwith labels, units, and evenlymarked out intervals.
Conclusion Questions
1. Is there a trend to your graphs and your data? Explain.
2. We varied the height (and indirectly, the speed) and the mass of theasteroid.What might be other factors we did not consider that mayalso affect the size of craters left behind by an asteroid? (think of atleast 2)
3. For the 2 factors that you listed above, give a hypothesis for each.How do you think these factors would affect the craters size?
4. In addition to the radii of the craters, what other qualities of thecraters could be measured or studied?
5. How do you think the angle of impact might affect the size or shapeof the crater left behind? Provide sketches in addition to words toanswer this question.
6. In scientific terms, how have comets and asteroids played a role in theevolution and development of the terrestrial planets in our solarsystem? Be specific for each planet: Mercury, Venus, Earth, Mars,
and the Moon.