1. Chapter 28.4 Asteroids, Comets & Meteoroids
Std 1f: Know the evidence for the dramatic effects that asteroid impacts have had in shaping the surface of planets and their moons and in mass extinctions of life on Earth
Objective 1: Describe the physical characteristics of asteroids and comets
Objective 2: Describe the Kuiper Belt and the Oort Cloud
Objective 3: Compare meteoroids, meteorites and meteors

2. Asteroids Asteroids - a small, rocky object that orbits the sun
The largest of the small bodies in the solar system
More than 50,000 have been discovered
The larger asteroids are known as “minor planets”

3. Asteroid Belt
Most asteroids are located in a region between Mars and Jupiter known as the Asteroid Belt

4. Composition of Asteroids
Composition (made out of) is similar to inner planets
3 categories of asteroids composition:
1) Silicate materials
2) Iron & Nickel
3) Carbon material (rarest)

5. Near-Earth Asteroids
More than 1,000 asteroids have orbits that bring them very close to Earth
Asteroids could strike Earth causing significant damage
Asteroid detection programs track these near-Earth asteroids to help predict possible collisions

6. Comets
Comets - small bodies of ice, rock and cosmic dust with an elliptical orbit around the sun
It gives off gas and dust in the form of a tail as it passes close to the sun
Most famous is Halley’s Comet which passes by Earth every 76 years (last time 1986)
Hale-Bopp passed by in 1997

7. Composition of comets Comets have several parts:
Core (nucleus)- made of rock, metals, and ice
Coma- a spherical cloud of gas and dust surrounds the core (core & coma form the head of the comet)
Tail- form when sunlight changes the comet’s ices to gases. Solar wind pushes the gas away from the sun

8. Objective 1: Describe the physical characteristics of asteroids and comets
Where are most asteroids found?
Between Mars and Jupiter (Asteroid belt)
What are the 3 different compositions of asteroids?
Silicate materials, nickel and iron, and Carbon
What is a small, icy, rocky object that orbits the sun?
comet
What are the 3 parts that make up a comet?
Core, coma, tail

9. Comets

10. The Oort cloud Most comets originate in the Oort cloud
Oort cloud - a spherical cloud of dust and ice that surrounds the solar system and extends from the Kuiper belt to almost halfway to the nearest star
Long-period comets – comets that take more than 200 years to complete one orbit of the sun

11. The Kuiper belt Pluto may be the largest body in this belt
Kuiper belt - A region of the solar system just beyond the orbit of Neptune that contains small bodies of mainly ice

12. Objective 2: Describe the Kuiper Belt and the Oort Cloud
Where is the Kuiper belt located?
Beyond Neptune
Where is the Oort cloud located?
Surround the solar system almost to the next star
Where do most comet originate?
Oort cloud
What is the largest body in the Kuiper belt?
Pluto

13. Short period comets
They take less than 200 years to complete one orbit around the sun
Halley’s comet is a short period comet

14. Meteoroids (in space)
Meteoroids -A relatively small, rocky body that travels through space
Diameter is less than 1mm
They are probably pieces of matter that come from passing comets
Produce meteor showers
Lyrid meteor shower (caused by dust from Thatcher comet)
Peaks April 22 (best viewing 3:30 – 4:40am)

15. Meteors (in the atmosphere)
Meteors -A bright streak of light that results when a meteoroid burns up in Earth’s atmosphere
Meteors are commonly called shooting stars
Meteoroids sometimes vaporize very quickly in a brilliant flash of light called a fire ball
Meteor shower - A large number of small meteoroids entering Earth’s atmosphere in a short period of time
D New report
Amazing video

16. Meteorites (hits Earth)
Large meteors may not burn up completely in the atmosphere
If it hits the Earth’s surface it is known as a meteorite
3 types of meteors:
1) Stony
2) Iron
3) Stony iron

17. Objective 3: Compare meteoroids, meteorites and meteors
What is a small rocky body that travels through space?
meteoroid
What is the bright streak of light caused by meteoroid burning up?
meteor
What is a meteor that hits the Earth?
meteorite
What are 3 types of meteors?
Stoney, iron, stoney iron