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

2. 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.

3. 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 tail is 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 icy, hard part of the comet is called the nucleus.
The gas and dust are released and form an atmosphere around the comet called the coma.
The tail always points away from the sun due to the solar winds (movement of heat away from sun)

4. Comets………Dirty Balls of Ice
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.

5. 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)

6. 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.

7. 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 (“Big Bang”).

8. Meteors…Shooting Stars or Space Garbage
Meteoroids
Pieces of rock or metal that travel in orbits around the sun.
Meteors
Pieces of rock/metal that are falling through the Earth’s atmosphere from space.
Meteorites
Pieces of rock/metal that have survived the heat caused from the friction of traveling through the atmosphere and have HIT THE GROUND.

9. Meteorite composition
Major groupings:
Stony meteorites
Chondrites
Achondrites
Iron meteorites
Stony-iron meteorites 9

10. Chondrites
Stony meteorites – most common meteorites and represent the oldest solids that are the building blocks of the solar system
Contain up to 80% chondrules
Chondrule- fragments that make up the chondrite
Subtypes:
Breccia- VERY large chondrules
Carbonaceous chondrites
dark because of the materials present 10

11. Achondrites
NO Chondrules are present because the materials have been heated and pressurized melting it together.
Similar to igneous rock (colors and lines are determined by the minerals in the meteorite).
The Johnstown Diogenite.
Lunar Meteorite Allan Hills 81005 11

12. Is there a fusion crust present?
Fusion crust forms on entry through the atmosphere. It looks like an outer coating. 12

13. Identifying a meteorite
Are there visible chondrules (large fragments)?
What color is the meteorite?
Is there a fusion crust?
Fusion crust forms during entry into the atmosphere. The heat melts the outside of the meteorite forming a “crust.” 13

14. Barringer Meteor Crater, Arizona, formed from Canyon Diable Meteorite
Impact Craters
Barringer Meteor Crater, Arizona, formed from Canyon Diable Meteorite 14

15. Impact Craters
Craters formed when a meteorite hits a solid surface on the Earth.
Size and depth will depend on the size of the meteorite and the speed it is falling.
Many meteorites will break into fragments upon impact. The type of surface will determine how far they scatter and how easy it is to find the pieces.
It is easier to find meteorite fragments in snow and sand
It is harder to find meteorite fragments in rocky areas or grassy fields.
Clearwater lakes, Quebec – 36+26km diameter, 290 ma 15

16. What’s That Up In The Sky???
COMETS
ASTEROIDS
METEORS
Made of ice-have tails
Made of rock and metal
Stay in space
Fall into Earth’s atmosphere
Orbit the sun
Gravity pulls to Earth; they burn up as they fall

17. What's the difference between meteoroids, meteors, and meteorites?