Download Kuiper Belt

Chapter 23 Section 4
Minor Members of Our
Solar System
Asteroids
Comets
Meteoroids/Meteors/Meteorites
Kuiper Belt
Oort Cloud
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
Why track asteroid paths?
NASA Capture Pet Asteroid?
PHAs (Potentially Hazardous Asteroids)
Location of Asteroids
Comets
• Rocky, metallic
material held together
by frozen gases (water,
ammonia, methane, CO2, and CO)
• Elongated orbits (far beyond Pluto) Space Debris Song
– 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)
Halley’s Comet
-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
Kuiper Belt & Oort Cloud
Kuiper Belt
•
•
•
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
Closer Look at the Kuiper Belt
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
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