Transcript File

What’s That Up In The Sky???
The difference between
Comets, Meteoroids and Asteroids
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 tails arer 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/come
t_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.
Deep Impact animation
Comets………Dirty Balls of Ice
After 500 or so passes
near the Sun, 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.
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
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
Meteors…Shooting Stars or Space
Garbage
Meteors are also called shooting
stars, but they 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)
Hey kid, wanna buy a meteorite?
http://www.alaska.net/%7Emeteor/
SZH.htm
Meteors…Shooting Stars or Space
Garbage
Astronaut Chris Hadfield
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!
Meteors…Shooting Stars or Space
Garbage
Meteors are falling all
the time.
On a clear, dark night
you may see one.
During some 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
ASTEROIDS
METEOROIDS
Made of ice, dust Made of rock and Made of rock and
and rock-have
metal
metal
tails
Stay in space
Stay in space In space, but fall into
Earth’s atmosphere
(meteors) sometimes
hitting Earth
(meteorites)
Orbit the sun
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/p
art5/section-29.html