1. Chapter 23 Section 4 Minor Members of Our Solar System
Asteroids
Comets
Meteoroids/Meteors/Meteorites
Kuiper Belt
Oort Cloud

2. Asteroids Small rocky bodies; irregular shape
Lie between orbits of Mars & Jupiter (asteroid belt)
Orbital period of 3-6 years
Some asteroids have very eccentric orbits & travel close to the Sun.
Others (larger) regularly pass close to Earth & Moon
Largest asteroid: Ceres—1,000 km diameter
3 types of asteroids:
--C (carbonaceous) 75% pop….outer belt
--S (silicaceous) 17% pop…inner belt…most common
--M (metallic) 8% pop…middle belt
NASA Capture Pet Asteroid?
PHAs (Potentially Hazardous Asteroids)
Why track asteroid paths?

3. Location of Asteroids

4. Comets Rocky, metallic material held together by frozen gases (water,
ammonia, methane, CO2, and CO)
Elongated orbits (far beyond Pluto)
Orbital period of most  hundreds of thousands of years
Some less than 200 years and encounter inner solar system
Anatomy of a comet:
Coma-glowing head produced as frozen gases
vaporized
Nucleus-located in the coma; icy
Tail-typically forms as approach Sun (can extend
millions of km); always points AWAY from Sun in
curved manner
Radiation pressure—forms dust tail
Solar wind– forms ionized (gas) tail (mainly CO)
Space Debris Song

5. Halley’s Comet Comet Ison -Periodic comet -Passes Earth every 76 years
-Last pass: 1986
-Next pass: 2061
Comet Ison
-Originated from Oort Cloud
-Most agree it did not survive
orbit around Sun

6. Kuiper Belt & Oort Cloud
Birthplace of short orbital period comets; nearly circular orbits roughly in same plane of planets
Located beyond Neptune
Most comets we see are Kuiper Belt comets
Oort Cloud
Birthplace of long orbital period comets; highly eccentric orbits; not confined to plane of solar system
“3-D shell” around solar system
Very rarely do we observe an Oort Cloud comet
Closer Look at the Kuiper Belt

7. Meteoroids Meteoroid: small solid particle in space; made of iron
Originate from: interplanetary debris, asteroid belt, or remains of a comet
Meteor: meteoroids that enter Earth’s
atmosphere; burn once in atmos.
Where does light originate?
Meteor showers  Earth encounters swarm of meteoroids traveling same speed/direction  link to comets…WHY?
Meteorite: reaches Earth’s surface
Meteor Crater Winslow, Arizona
~50,000 years ago
Originated from asteroid belt
~26,000 mph prior to impact; 150 ft across
Crater is roughly
1 mile wide
2.4 mile circumference
550 feet deep