Download Comets - LWC Earth Science

Minor Members of
23.4 the Solar System
Chapter
Students will be able to…
•Identify where most asteroids are located
•Describe the structure of a comet
23.4 Asteroids: Microplanets
 Definition - An asteroid is a small, rocky body whose
diameter can range from a few hundred kilometers to
less than a kilometer.
Do asteroids have an atmosphere?
None of the asteroids have atmospheres.
What is another name for asteroids?
Asteroids are also known as planetoids or minor
planets.
23.4 Asteroids: Location
 Most asteroids lie between the orbits of
Mars and Jupiter. They have orbital periods
of three to six years.
Asteroids
• Why is there an asteroid belt?
• One theory suggests that they are
the remains of a planet that was
destroyed in a massive collision
long ago.
• More likely, asteroids are material
that never coalesced into a planet.
• In fact, if the estimated total mass
of all asteroids was gathered into a
single object, the object would be
less than 932 miles across -- less
than half the diameter of our Moon
Some examples of asteroids
Name: Gaspra
Size: 17 x 10 km
This image was taken in October
1991, when the Galileo spacecraft
passed within 1600 km on its way
to Jupiter. (Courtesy Nasa/JPL)
Name: Ida
Size: 56 x 24 km
Location: Asteroid Belt
Image obtained in 1993
when Galileo passed within
2400 km (Courtesy
Nasa/JPL).
Asteroids vs. Meteoroids
- Asteroids are big and meteoroids are small
(pebbles)
Meteoroids come from:
1) left over solar system debris
2) asteroids collide
3) comet debris.
Asteroid, Meteoroid, Meteor, and Meteorite
- When a meteoroid strikes our atmosphere at high
velocity, friction causes this chunk of space matter to
heat up and create a streak of light known as a meteor
(shooting star).
Asteroid, Meteoroid, Meteor, and Meteorite
- If the meteoroid does not burn up completely, what's
left strikes Earth's surface and is called a meteorite.
These rocks have helped identify the age of the solar
system (4.6 billion years old).
Major Meteor Showers
The New Solar System
23.4 Comets
 Comets are small bodies made of rocky
and metallic pieces held together by frozen
gases.
 Comets generally revolve about the sun in
elongated orbits (highly elliptical).
23.4 Parts of a Comet
• A coma is the fuzzy, gaseous component of a comet’s
head (atmosphere).
• A small nucleus (body) with a diameter of only a few
kilometers can sometimes be detected within a coma.
• As comets approach the sun, some, but not all, develop
a tail that always points away from the sun.
23.4 Parts of a Comet
23.4 Comets
 Kuiper Belt or Oort Cloud
• Where most comets are located.
• This area is found beyond Neptune
Comets
Comets
• Astronomers believe
that comets are leftover
debris from the outer
planets about 4.6 billion
years ago.
• Some scientists believe
that comets originally
brought to Earth some
of the water and the
carbon-based
molecules that make up
living things.
23.4 Comets
 Halley’s Comet
• The most famous short-period comet is Halley’s
comet. Its orbital period is 76 years.
• From July 16 through July 22, 1994, pieces of an
object designated as Comet P/Shoemaker-Levy
9 collided with Jupiter. This is the first collision of
two solar system bodies ever to be observed
• Comet Shoemaker-Levy 9 consisted of at least
21 fragments
• http://www.windows.ucar.edu/tour/link=/co
mets/comet_model_interactive.html