1. COMETS

2. Comets contain a nucleus, dust tail and an ion tail
A comet is a small body of ice, rock, and cosmic dust loosely packed together
Comets contain a nucleus, dust tail and an ion tail

3. COMETS
Referred to as DIRTY SNOWBALLS due to their composition
Probably left over from the time when the planets formed

4. COMETS

5. dust tail and an ion tail Center is the nucleus
COMETS
Passes close to the sun, solar radiation heats the comet and gas and dust stream off in the form of a LONG TAIL
TWO TYPES OF TAILS
dust tail and an ion tail
Center is the nucleus

6. COMETS
Elongated orbits
Ion tail always POINTS AWAY from the sun – ion tail is blown away by solar wind (made of ions)
Dust tails don’t always point away from the sun

8. COMETS Scientists think that comets come from:
Oort Cloud, spherical region that surrounds the solar system
When gravity of a passing planet/star disturbs part of the cloud, comets can be pulled toward the sun.
Kuiper belt, which is the region outside the orbit of Neptune.

9. ASTEROIDS

10. ASTEROIDS Small, rocky bodies that revolve around the sun
Irregular shapes
Orbit in the ASTEROID BELT – wide region between the orbits of Mars and Jupiter
Thought to be material left over from the formation of the solar system

11. Asteroid Belt

12. Types of Asteroids
Outermost region of asteroid belt - asteroids are dark reddish brown (may be rich in organic material)
Asteroids – dark gray surfaces – rich in carbon
Inner most region – asteroids are light gray (stony or metallic composition)
Examples: Hektor, Ceres, Vesta

13. Examples of Asteroids

14. METEOROIDS
Meteoroid - A small, rocky body that revolves around the sun – probably pieces of asteroids
Meteorite – meteoroid that enters earth’s atmosphere and strikes the ground
Meteor – bright streak of light caused by a meteoroid/comet dust burning up in the atmosphere

15. Meteor

16. Meteors
Meteor Shower- happen when Earth passes through the dusty debris that comets leave behind

17. Types of Meteorites

18. IMPACT
CRATERS

19. IMPACT CRATERS
When an object in space collides with another object in space – impact crater
Planets/moons with no atmospheres have MORE IMPACT CRATERS
Atmosphere acts as a shield – smaller objects “burn up”

20. Impact Craters
Every few thousand years impacts may be powerful enough to cause a natural disaster
Impact that is large enough to cause a global catastrophe are estimated to happen once every few hundred thousand years, on average

22. TORINO SCALE
System that allows scientists to rate the hazard level of an object moving toward Earth
0 = small chance of hitting Earth
10 = definitely will hit Earth