Transcript Meteors, Asteroids, and Comets!

Meteors!
Meteoron – Greek for thing in the sky
meteor - objects that fall through and burn up
in the Earth’s atmosphere. Most are small
grains of rock or metal. They produce streaks
of light called shooting or falling “stars.”
meteorite – a meteor that hits the earth
meteoroid – a chunk of rock or dust in space
meteor shower - When many meteors fall
through the atmosphere in a short time.
Meteor showers are formed mainly by comets
that come too close to the Sun. Heat from the
Sun causes dust and rock to break off the
comet’s nucleus. This continues to move along
the comet’s orbital path. If Earth’s orbit crosses
this path, the dust particles burn up in the
atmosphere to produce a meteor shower.
Starry night video clip
http://antwrp.gsfc.nasa.gov/apod/ap080911.html
http://antwrp.gsfc.nasa.gov/apod/ap080103.html
http://antwrp.gsfc.nasa.gov/apod/ap061119.html
The Peekskill meteor of 1992
was captured on 16
independent videos and then
struck a car. Documented as
brighter than the full Moon, the
spectacular fireball crossed
parts of several US states
during its 40 seconds of glory
before landing in Peekskill, New
York. The resulting meteorite,
pictured here, is composed of
dense rock and has the size
and mass of an extremely
heavy bowling ball. If you are
lucky enough to find a meteorite
just after impact, do not pick it
up -- parts of it are likely to be
either very hot or very cold.
Asteroids!
Asteroids –Rocky objects revolving around the sun that are
too small and numerous to be considered planets.
Asteroid belt – The region of the solar system, between the
orbits of Mars and Jupiter, where many asteroids are found.
It is currently thought that the asteroid belt is material that
did not form a planet because of Jupiter’s strong gravity.
Galileo image of Gaspra
www.windows.ucar.edu
Comets!
Comet – a loose collection of ice, dust, and small
rocky particles, typically with a long, narrow orbit. A
dirty snow ball!
Comet means “hairy star” in Latin!
Most comets are hidden from us in the Kuiper belt
or Oort cloud.
Periodic comets – ones that keep returning to the
earth on a regular basis – probably come from the
Kuiper belt.
Non-periodic comets - comets that swing around
the Sun once and are flung off into space probably come from the Oort cloud.
There are 2 parts to a comet, the head and the
tail. The head is made up of the coma and the
nucleus.
As a comet approaches the sun, the energy turns
the ice into gas releasing gas and dust.
Some of this streams outward, forming a tail.
There can be a gas tail and a dust tail. The gas
tail always points away from the sun.
http://www.windows.ucar.edu/tour/link=/comets/comet_model_interactive.html
Comet Hale-Bopp's blue ion tail, consisting of ions from the comet's nucleus, is pushed
out by the solar wind. The white dust tail is composed of larger particles of dust from the
nucleus driven by the pressure of sunlight, that orbit behind the comet. Observations
showed that Comet Hale-Bopp's nucleus spins about once every 12 hours.
http://antwrp.gsfc.nasa.gov/apod/ap080302.html
Since brightening unexpectedly by nearly one million fold
in late October, the last three months have found the
coma of Comet 17P/Holmes both expanding and fading.
This spectacular composite image shows how the coma
and tail of Comet Holmes have changed. Due to Earth's
changing vantage point, Comet Holmes, out beyond the
orbit of Mars, was seen in November nearly head-on, but
in recent months is seen more from the side.
Additionally, the comet's motion, when combined with
Earth's changing perspective, has caused the comet to
have shifted relative to the background stars. The curved
path of Comet Holmes shows it to be undergoing
apparent retrograde motion as the Earth orbits quickly in
front of it. (2007-2008)
http://antwrp.gsfc.nasa.gov/apod/ap080205.html