1. COMETS, ASTEROIDS, METERORS, AND METEROIDS!

2. COMETS
Astronomers believe that comets are leftover debris from a collection of gas, ice, rocks, and dust that formed the outer planets about 4.6 billion years ago.
Some scientists believe that comets originally brought to Earth some of the water and the carbon-based molecules that make up living things.

3. A comet is an icy body that releases gas or dust.
“Dirty Snowball”
Because comet tails are pushed by solar radiation and the solar wind, they always point away from the sun.

4. Most comets are found in the Kuiper belt (beyond the orbit of Pluto) and the Oort cloud (about 1,000 times farther away from the sun than Pluto's orbit). We will focus on the Halley’s Comet!

5. Halley's Comet
Halley's Comet last appeared in the inner Solar System in 1986, and will next appear in mid-2061.
SIZE: 15 kilometres long, 8 kilometres wide and perhaps 8 kilometres thick
15 km is about 9.3 miles!

6. ASTEROIDS

8. Asteroids are leftover pieces of the early solar system that never came together to form a planet.
Most asteroids revolve around the sun between Mars and Jupiter….the asteroid belt!

9. Theory: Asteroid or comet impact, ~ 6
Theory: Asteroid or comet impact, ~ 6.2 miles wide, travelling 150 times faster than a jet, struck off the coast of the Yucatan Peninsula 65 million years ago. Did that happen…yes! Did that destroy the dinosaurs….?
Can this type of mass extinction occur again?

10. NASA Jet Propulsion Laboratory California Institute of Technology - Interactives: Keeping an Eye on Space Rocks
In 2028 the asteroid 1997 XF 11 will come very close to the Earth. It will miss unless some keyhole gravitational event causes it the change its orbit and hit the Earth. That would mean that a mile wide asteroid would be hitting the planet at 50,000 kph. It would release enough energy to equal 1 million megatons. That is 10 million times the energy of the bomb that dropped on Hiroshima. Nearly all life on this planet would be gone within a year!
"Awesome Asteroids“
Don’t worry, nothing too big should hit within the next few centuries!

11. Thankfully so…check out the results of past strikes!
49,000 years ago!
~ 150 ft. wide meteorite
Arizona

12. 8 mile wide crater!
100 – 140 m.y.a
Canada

13. 15 mile diameter and goes down to 16,400 ft!
142 m.y.a
Equivalent to 22,000 megatons of TNT
Australia

14. METEOROIDS, METEORS & METEORITES
A meteoroid is a chunk of rock or dust in space.
When a meteoroid enters Earth’s atmosphere it is classified as a meteor, or a shooting star.
If that meteor isn’t burned up by Earth’s atmosphere and makes it to Earth’s surface it is called a meteorite!

15. On average, a meteor streaks overhead every 10 minutes.
2009 Meteor Showers

16. Some 500 meteorites hit Earth annually, but only five or six are recovered. Very few meteorites are large enough to make a crater….this one did!
Carancas, Peru, 2007
The meteorite's impact sent debris flying up to 820 feet away, with some material landing on the roof of the nearest home 390 feet from the crater. The resulting crater resembled a muddy pond measuring 42 feet wide and 10 feet deep.