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Minor Members of the Solar System
Today you will learn:
1. What other objects, besides the planets, orbit
around the sun.
2. The difference between asteroids, meteors, and
comets.
Introduction
In 2001, the NEAR
Shoemaker was the first
visitor on asteroid Eros.
This space probe found
that it has dust and
rocks on its surface.
I. Asteroids
A. Asteroids are called
microplanets or “flying
mountains” because
they are small rocky
bodies.
1. They can be 1000 km
wide or the size of a
grain of sand.
Asteroids (cont)
2. They lie between the orbits of Mars and Jupiter and
their orbital period is 3-6 years.
3. Astronomers hypothesize that the astroids are
remnants of a planet that was 1/1000 the size of
Earth.
B. Comets
1. Comets are pieces of
rocky and metallic
materials held together
by frozen gases (water,
methane, ammonia,
carbon dioxide)
2. They travel in
elongated orbitals.
a. Take 200 to 100,000 yrs
to orbit the sun.
3. Anatomy of the comet.
a. Coma is the head of the
comet of vaporized
gases (from getting hot
from the sun).
b. It has two tails that can
extend for millions of
km.
Comets (cont)
c. One tail is made of
dust, the other is made
of ionized gases from
the solar wind.
d. The tail always points
away from the sun.
e. Once far from the sun,
it becomes “cold” and
doesn't have a tail
anymore.
C. Famous Comets
1. Haily's Comet: orbits
every 76 years.
a. Has tail that is 1.6
million km long.
b. Been recorded 29
times since 240 BC.
c. It passed by Earth last
in 1986.
Famous Comets (cont)
2. Hale-Bopp comet:
passed through Earth's
orbit in 1997.
a. Brightest comet to pass
Earth and could be seen
by the naked eye.
b. 100 x brighter than
Hailey's comet.
D. Source for Comets
1. Comets with short orbital periods come from the
Kuiper Belt.
a. The Kuiper Belt lies outside of Neptune. (Pluto
was believed to come from here)
2. Comets with long orbital periods come from the
Oort Cloud.
a. This is a sphere of comets that surrounds the solar
system.
E. Meteoroids
1. Small solid particles
that travel through
space.
2. They come from:
-Remnants of comets
-The astroid belt
-Interplanetary debris
F. Meteors
1. When a meteoroid
enters Earth's
atmosphere, it burns up
due to the friction of the
atmosphere's particles.
2. Meteor showers occur
when multiple meteors
enter Earth's
atmosphere.
Meteors (cont)
3. The Perseid meteor
shower occurs around
August 12 every year.
4. It is believed to be
caused by the remnants
of a comet that passed
in 1862.
G. Meteorites
1. When a meteor
actually hits Earth's
surface.
2. In northern Arizona, is
the Meteor Crater,
which is 1 mile wide
and ½ mile deep.
The Meteor Crater in Arizona