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What’s That Up In The Sky???
The difference between
Comets, Meteors and Asteroids
by Jennifer Powers
Comets………Dirty Balls of Ice
They look like a star
with a ghostly white
tail.
The term "comet"
derives from the
Greek aster
kometes, which
means "long-haired
star"---a reference to
the tail.
http://comets.amsmeteors.
org/educate/hbmovie.m
pg
Comets………Dirty Balls of Ice
They can be seen by us only when they pass by the sun
and the sun’s heat melts them.
The comet's tail is made of material from the comet; gas
from the ices and dust that is mixed in with the ice.
They escape as the comet melts.
The tail always points away from the sun due to the
solar winds (movement of heat away from sun)
Comets………Dirty Balls of Ice
They travel around the sun in long looping orbits that
bring them near the sun on one end and around
Jupiter on the other end. Example:
http://www.windows.ucar.edu/tour/link=/comets/comet
_model_interactive.html
If a comet has a large orbit, it takes a long time to go
around the Sun. Some comets are "short-period"
comets that take five or ten years to complete an
orbit. Some comets are "long-period" comets that
take decades, centuries, or millenia to orbit the Sun.
Comets………Dirty Balls of Ice
The icy, hard part of the comet is called the nucleus. As
the comet melts, sometimes large chunks of ice
break off in a hurry and large amounts of gases
escape at once and cause a bright “outburst”.
The gas and dust are released and form an atmosphere
around the comet called the coma.
http://www.nasa.gov/mov/120698main_Outburst%20Mo
vie-070305.mov or
http://deepimpact.jpl.nasa.gov/gallery/animation.html
Comets………Dirty Balls of Ice
After 500 or so passes
near the Sun off
most of a comet's
ice and gas is lost
leaving a rocky
object very much
like an asteroid in
appearance.
Comets………Dirty Balls of Ice
How did comets form???????
Astronomers are not certain how comets formed,
but most believe that comets formed at the same
time our solar system did, perhaps even in
among the planets. Comets are made of a
mixture of ices (water, methane, carbon dioxide,
etc) and dust. These are precisely the materials
that probably existed when the solar system was
forming.
Will you be the future scientists who answer this
question?
Comets………Dirty Balls of Ice
What are scientists doing to learn more about comets?
Deep Impact: NASA’s space probe: The mission is attempting to
bring a spacecraft and a comet together at truly out-of-this-world
speeds so we can learn about the interior of a comet.
http://www.jpl.nasa.gov/multimedia/deep-impact/index-flash.html
http://www.nasa.gov/mov/117656main_Maas_DI_Short_320x24
0.mov or http://deepimpact.jpl.nasa.gov/gallery/animation.html
Hitting the Surface:
http://www.nasa.gov/mov/121493main_Impactor%20POV%20to%2
0crash.mov or
http://deepimpact.jpl.nasa.gov/gallery/animation.html
Asteroids……Rockin’ Around
Asteroids are
LARGE chunks
of rock and metal
that orbit the sun.
They range from just
over ½ a mile (1km)
to a few hundred
miles in diameter
(diameter = how
wide across)
Asteroids……Rockin’ Around
Most asteroids travel in
the wide gap between
the inner planets and
outer planets (between
Mars and Jupiter).
But a few travel in paths
across Mar’s orbit and
some even cross in
Earth’s orbit.
Asteroids……Rockin’ Around
Most of the chunks or
rock and metal in
space came
together long ago to
form the planets and
moons.
Asteroids are left-over
pieces of rock from
when the solar
system was formed.
Asteroids……Rockin’ Around
Are scientists studying asteroids?
They are NEAR: NEAR Shoemaker is the first spacecraft
mission specifically designed to study an asteroid. It was
launched on February 17, 1996 on a 4-year journey to the
near Earth asteroid 433 Eros. The objective of the mission
was to encounter and orbit Eros for one year to collect
imagery and gather data on the asteroid's properties such
as surface features, composition, and rotation. The
mission was successfully completed in February 2001
when a previously unplanned landing was executed. This
was the first time a spacecraft ever landed on an asteroid.
http://near.jhuapl.edu/media/010131_pc/movie/NEAR_desce
nt_small.mov
http://near.jhuapl.edu/iod/20010214/index.html
Asteroids……Rockin’ Around
The Anatomy of Asteroid Names
Sometimes it seems that astronomers enjoy picking nonsense names for
the objects they study. What person on the street would guess that
"2000 QW7" is a fascinating space rock? Nevertheless, there is a
method to this naming madness.
So many new asteroids are discovered each month that astronomers need
an efficient way to catalog them. The first part of "2000 QW7" is simple
-- it identifies the year of the asteroid's discovery (2000).
Then comes "QW7." The first letter tells us that the object was identified
during the second half of August. Each half-month is identified with a
letter of the alphabet. January 1st-15th = "A"; January 16th-31st = "B";
August 16th-31st = "Q", etc. The letter "I" is omitted in this system.
The second and third characters "W7" are a shorthand way of counting the
number of asteroids found during the 2nd half of August 2000. The first
asteroid discovered was "2000 QA"; the second was "2000 QB;" The
second letter cycles through the alphabet until it reaches "Z" and then it
goes back to the beginning with an extra number. So, the 26th asteroid
discovered during the second half of August 2000 was "2000 QA1".
Remember that "I" is omitted, so "A1" corresponds to the 26th asteroid,
not the 27th. This means that 2000 QW7 was the 197th asteroid found
in the second half of August 2000!
Meteors…Shooting Stars or Space
Garbage
Meteors are also called
shooting stars
Meteors are small pieces of
space debris (junk) pulled
into Earth’s atmosphere by
gravity.
Meteorites are metallic rocks
broken off from asteroids
and comets
Meteors fall to Earth at
speeds from 22,000 MPH
to 64,000 MPH (8x shuttle
speed)
You Can Buy Meteorshttp://www.alaska.net/%7Eme
teor/SZH.htm
Meteors…Shooting Stars or Space
Garbage
Most meteors are only as
big as a grain of sand.
Most burn up while
entering Earth’s
Atmosphere
However………………
They can be bigger.
Craters in the Earth and
ones studied below the
surface show that one
about the size of a
house landed about
250,000 years ago! Is
that what killed the
dinosaurs???
Meteors…Shooting Stars or Space
Garbage
Meteors are falling all
the time.
http://comets.amsmete
ors.org/educate/vde
mo2b.mpg
On a clear, dark night
you may see one.
During the annual
meteor storms, you
may see 100 per
hour.
Meteors…Shooting Stars or Space
Garbage
How can something as small as a grain of sand light up
so brightly?
Entering the Earth’s atmosphere so fast creates a lot of
friction. The friction causes them to heat up and give
off light.
The light trail may stay in the sky for up to 30 minutes
and end with a “POP”.
REALLY bright meteors are called
FIREBALLS
What’s That Up In The Sky???
COMETS
Made of icehave tails
Stay in space
Orbit the sun
ASTEROIDS
METEORS
Made of rock Made of rock
and metal
and metal
Stay in space Fall into
Earth’s
atmosphere
Orbit the sun Gravity pulls to
Earth; they
burn up as
they fall
What's the difference between
meteoroids, meteors, and meteorites?
Difference between:
http://www.faqs.org/faqs/astronomy/faq/pa
rt5/section-29.html