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Solar System Debris: Minor Bodies of the Solar System. Asteroids Comets Meteoroids. ~few hundred miles. sand grain. How big?. Everywhere!. * Where are they?. . . . But concentrated mainly in the:. Main Asteroid Belt Kuiper Belt Oort Cloud. Asteroids. * Debris left-over
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Solar System Debris: Minor Bodies of the Solar System Asteroids Comets Meteoroids
~few hundred miles sand grain How big?
Everywhere! * Where are they? . . . But concentrated mainly in the: • Main Asteroid Belt • Kuiper Belt • Oort Cloud
* Debris left-over from solar system formation! Average separation 4 million miles p. 197
35 mi Ida & Dactyl
Asteroids viewed from Earth p. 198
20 mi Near-Earth Asteroids: Orbits pass near and/or cross Earth’s orbit. Asteroid 433 Eros
Asteroid 1994 XM1 Missed Earth by 65,000 mi!
Galaxy 4.6 hrs Kuiper Belt Object (KBO) 1993 SC * KBOs: mainly icy in composition ? Is Pluto just the largest KBO?
100,000 AU Oort Cloud some comets originate here p. 203
Many comets orbit well out of plane of planets’ orbits.
Comet Hyakutake (1996) ~ 50o
Nucleus: ice with intermixed ‘gravel.’ . Comet Hale-Bopp (1997) Ion tail: ions energized by solar photons. Dust tail: dust particles scatter (reflect) sunlight. p. 201
March 1, 2001: Hale-Bopp ~13 AU from Sun
Solar wind + radiation pressure Comet tails always point away from the sun. p. 202
Nucleus of Comet Halley “Dirty Snowball”
5 mi Comet Borrelly
Periodic comets eventually evaporate . . . Some break up near the sun . . .
* Stuff falls on Earth continuously – most of it harmlessly. Meteor– streak of light caused by heating of Meteoroid as it passes through Earth’s atmosphere.
Meteorite– piece of meteoroid that reaches the ground.
Large meteoroids: chipped from asteroids Small meteoroids: comet debris Meteor showers
Leonid Shower (mid-November)
Leo Radiant November, 2001
Leonid Storm of Nov 17, 1966
“Thirteen of us, mostly students, drove to observe and record the Leonids atop Kitt Peak on the night of Nov. 16-17, 1966. We formed a circle of chairs and began to study our assigned areas of the sky for meteors. It started off slowly, about 30/hour. After 3 hours it picked up dramatically, and we observed a peak of about 40/second that lasted for 10 to 20 minutes. This was 24,000 in a ten minute period, a rate of 144,000/hour. We stood in awe as the sky seemed filled with meteors.”