Meteors!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.htmlThe 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!

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.

www.windows.ucar.edu

Galileo image of Gaspra

Comets!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.

http://www.windows.ucar.edu/tour/link=/comets/comet_model_interactive.html

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://antwrp.gsfc.nasa.gov/apod/ap080302.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/ap080205.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)