Comets, Meteors, and Asteroids
Comets
 The
word "comet" comes from the Greek
word for "hair.”
 Our ancestors thought comets were stars
with what looked like flowing hair trailing
behind.
Comets: “Dirty Snowballs”
Structure of a Comet
 Comets
Ion Tail
Dust
Tail
Coma
To Sun
are loose
collections of ice,
dust, and small rocky
particles whose orbits
are usually very long,
narrow ellipses.
Comet Structure
 Nucleus
 10
km “Dirty Snowball”
 Coma
 Cloud
of evaporated ices and ions
 may be 100,000 km in diameter
 Tail
 Always
 Solar
 Dust
points away from Sun
Wind and Radiation Pressure
and Ion Tails
Comet’s Orbit
 Comets
move in an elliptical shaped orbit.
Where do comets come from?
The Oort Cloud
&
The Kuiper Belt
Comet Halley
Bayeaux Tapestry
Norman Invasion of 1066
Comet Halley 1910
•Pope Callixtus III
excommunicated
Halley's Comet in 1456
•In 1910, charlatans sold
"comet pills"
Comet Nucleus
Comet of 1577
Hyakutake
Hale-Bopp
Comet West
What does a comet leave behind?
Meteoroids
What happens when Earth
travels through the remains
of a comet’s tail?
Meteriods burn up in our
Atmosphere
Then we call
them METEORS
OR in this case…
A METEOR
SHOWER
After Midnight is Best to view
meteors…or meteor showers
Midnight
Rotational
Velocity
Orbital
Velocity
The 1833 storm
1997 meteors from Orbit
Two Showers for Halley in
the same year
Sporadic Meteorites
Irons
Stony-Irons
Carbonaceous
Chondrite
Chondrites
Achondrite
Barringer’s Crater
An iron meteorite 100 feet across and 70,000 tons
slamed into the Earth at about 43,000mph in the
Arizona desert near Flagstaff 40,000 years ago.
Barringer Crater is 4,100 feet wide and 571 feet deep.
Other Impact Craters
Tunguska, 1908
But when they cause this much
damage…they are usually called
ASTEROID COLLISIONS
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 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
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
Ida - Dactyl
Gaspra
Asteroids Elsewhere
Sedna
What’s That Up In The Sky???
ASTEROID
METEOROID
Large;
Smaller/small;
Made of rock Made of rock
and metal
and metal
METEOR
METEORITE
Smaller to
smallest:
Made of rock
and metal
Fall into
Earth’s
atmosphere
Small; Made
of rock and
metal
Stay in space
Stay in space
Orbit the sun
Orbit the sun Gravity pulls to
Earth; they
burn up as
they fall
On Earth’s
surface
What did not
burn up
Leaves a
crater