Comets, Asteriods, and Meteors PowerPoint

Comets, Asteroids,
and Meteors
By: Annette Miles
What is a comet?
A comet is a small
body which scientists
sometimes call a
planetesimal. They
are made out of dust,
rock, gas, and ____.
They are kind of like
a dirty _________.
Comets are made up of
different parts.
 The nucleus
 The coma
 The ion tail
 The dust tail
 The hydrogen envelope
center of a
The nucleus is the frozen _______
comet’s head. It is composed of ____,
gas and dust. The nucleus contains
most of the comet’s mass and measure
about 10 miles across or less.
The nucleus of Halley’s
The ______
coma is a spherical blob of gas that
surrounds the nucleus of a comet. As the
comet gets closer to the sun, the heat
vaporizes some of the ice and causes the
comet to spew gas and dust particles into
coma form the
head of a comet.
ion tail is made of ___________
The _________
charged gas molecules that are being
pushed away from the nucleus by the solar
_____. (The blue tail in the picture.)
When a comet is approaching the Sun, the
trails the comet: when the comet is
ion tail _______
leaving of the Sun, the ion tail leads
_____. The tail
fades as the comet moves far from the Sun.
The ion tail
can be well
over 100
million km
The _________
dust tail develops
when the comet is _____
the Sun. This tail is
made of small dust
particles that have
evaporated from the
nucleus and are being
pushed away from the
comet. The tail _______
slightly due to the
comet’s motion.
The tail can be
up to 250
million km
long, and is
most of what
we see. Comets
are only visible
when they're
near the sun in
their elliptical
Comet Hale Bopp showing its two tails.
Courtesy of NASA
Hale-Bopp – The Great
Comet of 1997
Surrounding the coma
is an invisible layer of
hydrogen that has
been released. It is the
hydrogen envelope .
This cannot be seen
from Earth because its
light is absorbed by
our atmosphere. It is
usually between the
ion tail and the dust
Can you identify the following parts of a comet?
Ion tail
4. Hydrogen envelope
Dust cloud
Comets orbit the Sun in highly _________
increases greatly when
orbits. Their speed _________
slows down at
they are near the Sun and ______
the far reaches of the orbit. Since the comet
is light only when it is near the Sun, comets
are dark throughout most of their orbit.
Comets originate from either the _______
Belt (beyond the orbit of Neptune) or the
Cloud (which surrounds the outer
reaches of the solar system.)
Videos on Comets
Animation of a Comet
rocky or _________
metallic objects,
Asteroids are _______
planetoids or minor planets
also know as____________
that revolve around our Sun.
Most asteroids orbit the Sun in the asteroid
Mars and _________.
belt located between _______
A few asteroids approach the Sun more
closely. The asteroids in the asteroid belt
elliptical orbit.
have a slightly __________
The time for one
revolution around
the Sun varies
from about
3 to 6 Earth
Asteroids range in size from tiny pebbles to
about 578 miles (930 kilometers) in
Sixteen of
the 3,000
are over 150
miles (240
km) in
• Asteroid Ceres
• Diameter of 590miles
(950 km)
• Largest asteroid and
only dwarf planet in
the inner Solar System
• Asteroid Vesta
• Diameter of 326
miles (525 km)
• Brightest asteroid
visible from the
Some asteroids even have orbiting moons
Here is the asteroid “243 Ida” and its tiny
asteroid moon, Dactyl. This is the first
asteroid ever found with an orbiting moon.
Ida's dimensions are about 35 x 15 x 13 miles.
Dactyl is only about 1 mile across.
small bodies that travel
Meteoroids are ______
through space. Most meteoroids are smaller
pebble Meteoroids are
than the size of a ________.
tiny particles left by an asteroid or a comet.
A meteor is a meteoroid that has entered
Earth’s atmosphere usually making
the _____________________,
a fiery trail as it falls. It is sometimes called
shooting star or a _______
a _________
falling star.
A meteor shower is a phenomenon in which
many meteors fall through the atmosphere
short time and in
in a relatively ______
approximately parallel trajectories.
Arizona, November 1966 - The Leonid meteor shower
rained 2,300 meteors per minute for 20 minutes.
(Photo NASA)
Video of meteor Shower
A meteorite is a meteor that has fallen and
______ the Earth. These rare objects have
survived a fiery fall through the Earth's
atmosphere and have lost a lot of mass
during that process.
Near Winslow, Arizona, you can visit a crater
that was made from a meteorite. The crater is
nearly one mile across, 2.4 miles in circumference,
and more than 500 feet deep.
Animation on the formation of this crater.

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