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Meteoroids, Meteors,
Meteorites, Asteroids &
Comets
What are asteroids?
An asteroid is a large rock in outer
space. Some can be very large, while
others are as small as a grain of sand.
Due to their smaller size, asteroids do
not have enough gravity to pull
themselves into the shape of a ball.
While most asteroids can be found in the Asteroid Belt, others are in
strange orbits straying far from home. It is currently believed that at
least 5000 asteroids cross the Earth's orbit, some coming very close.
Don't worry though, asteroids and comets only hit the Earth every
100 million years or so.
Asteroid Belt
The asteroid belt is a
doughnut-shaped
group of small, rocky
objects. Most of these
objects orbit the Sun in
a belt between Mars
and Jupiter, but some
are in other orbits.
Asteroids that orbit
near the Earth are
called NEA's (Near
Earth Asteroids).
ASTEROID
MARS
BELT
JUPITER
Vocabulary
ASTEROID – a large rock in outer
space.
GRAVITY – the invisible force
between objects that makes objects
attract each other.
~Asteroids are chunks of rock and metal that
orbit around the Sun.
~ Scientists think that they are loose
material that never formed into planets.
~ The Main Asteroid Belt is located between
Mars and Jupiter.
~ More than 40,000 asteroids have been
discovered.
Meteoroids are…
3. pieces that come mostly
from asteroids, but also from
comets, the moon, and the
planet Mars.
About
Meteoroids
Click on the picture above.
Meteoroids are
small bodies that
travel through
space and orbit the
sun.
The fastest meteoroids travel at
roughly 26 miles per second (42
km per second) through space.
Meteors are…
Meteors are
meteoroids that
have entered
Earth’s atmosphere.
The friction between the fast-moving
meteor and the gas in the Earth's
atmosphere causes intense heat; the
meteor glows with heat and then
burns. This glowing phase usually
happens 50 to 68 miles (80 to 110
kilometers) above the Earth.
CLICK HERE TO SEE
A SHORT MOVIE
SHOWING A METEOR
“FIREBALL” MOVING
THROUGH SPACE.
Meteor Showers
If you have a dark, clear sky you will probably
see a few meteors per hour on an average night.
During one of the annual meteor showers you
may see as many as 100 per hour.
Our word meteor
comes from the
Greek word
meteoron which
means "a thing in
the sky."
Meteorites are…
One of the Martian
meteorites is
believed to show
evidence of early
life on Mars.
Meteorites are
meteors that have
fallen to the Earth.
At least 100 meteorites hit the
Earth every year. Most
meteorites burn up in the
Earth's atmosphere; all that is
left is a bit of dust.
What are comets?
Comets are small, icy bodies that orbit the sun.
They are made up of a solid nucleus (ice, gas, and
dust), a gaseous coma surrounding the nucleus,
and extremely long tails (both dust and gas tails).
The tails can be up to 250 million km long.
Vocabulary
COMET - A frozen chunk of ice and dust
in outer space.
“A Dirty Snowball”
ORBIT - The path followed by an object
in space as it goes around another
object.
Since comets have no
light of their own, how
are we able to see
them?
And the answer is...
Comets reflect light
from the Sun which
makes them visible to
us here on Earth.
The correct answer is…
Ice,
Gas,&
Dust
A Comets Orbit
Comets orbit the Sun in highly elliptical orbits.
Their velocity increases greatly when they are near
the Sun and slows down at the far reaches of the
orbit. Since the comet is light only when it is near
the Sun (and is it vaporizing), comets are dark
(virtually invisible) throughout most of their orbit.
Vocabulary
ELLIPTICAL - Shaped like an egg.
VELOCITY – quickness of motion.
PICTURE OF COMET SHOEMAKER-LEVY 9
When the comet was observed, its train of 21 icy fragments stretched
across 710 thousand miles (1.1 million km) of space, or 3 times the
distance between Earth and the Moon. The comet was approximately 410
million miles (660 million km) from Earth when the picture was taken, on a
mid-July collision course with the gas giant planet Jupiter.