Solar System Debris:Minor Bodies of the Solar System

Asteroids

Comets

Meteoroids

Howbig?

~few hundred miles

sandgrain

* Where are they?

Everywhere!

. . . But concentrated mainly in the:

1. Main Asteroid Belt

2. Kuiper Belt

3. Oort Cloud

Asteroids

* Debris left-overfrom solar systemformation!

Average separation 4 million miles

p. 197

Ida & Dactyl

35 mi

Asteroidsviewedfrom Earth

p. 198

Asteroid433 Eros

20 mi

Near-Earth Asteroids: Orbits pass near and/or cross Earth’s orbit.

Asteroid 1994 XM1

Missed Earth by 65,000 mi!

Comets

Kuiper Belt

Kuiper Belt Object(KBO) 1993 SC

4.6 hrs

* KBOs: mainly icy in composition ?

Is Pluto just the largest KBO?

Galaxy

OortCloud

somecomets

originatehere

100,000 AU

p. 203

Many comets orbitwell out of planeof planets’ orbits.

Comet Hyakutake (1996)

~ 50o

Comet Hale-Bopp(1997)

Ion tail: ions energizedby solar photons.

Dust tail: dust particlesscatter (reflect) sunlight.

Nucleus: ice withintermixed ‘gravel.’ .p. 201

March 1, 2001: Hale-Bopp~13 AU from Sun

Comet tails alwayspoint away from the sun.

Solar wind +radiation pressure

p. 202

Nucleus of Comet Halley

“Dirty Snowball”

Comet Borrelly

5 mi

Periodic comets eventually evaporate . . . Some break up near the sun . . .

. . . And some comets dive into the sun.

Meteoroids

* Stuff falls on Earth continuously – most of it harmlessly.

Meteor – streak oflight caused by heating of Meteoroidas it passes throughEarth’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)

Radiant

Leo

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.”