1. Shooting Star?

2. What’s That Up In The Sky???
The difference between
Comets, Meteoroids and Asteroids

3. 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.

4. 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)

5. 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:
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.

6. 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

7. 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.

8. 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.

9. 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.

10. 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)

11. 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.

12. 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.

13. 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.

14. 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?

15. 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!

16. 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.

17. 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!

18. What’s That Up In The Sky???
COMETS
ASTEROIDS
METEOROIDS
Made of ice, dust and rock-have tails
Made of rock and metal
Stay in space
In space, but fall into Earth’s atmosphere (meteors) sometimes hitting Earth (meteorites)
Orbit the sun
Gravity pulls to Earth; they burn up as they fall