1. IT CAME FROM Asteroids, comets, and YOU

2. Formation of the Solar System

3. Formation of the Moon

4. Luna

5. The Asteroid Belt is not like this

6. Chicxulub 65 million years ago 180 km wide

7. Barringer Meteor Crater (Arizona) 49,000 years ago 1.186 km diameter (0.737 miles)

8. Area surrounding the 1908 Tunguska Event, circa 1927

9. Artist’s Conception, just before impact

11. When will the next collision occur?

12. Asteroid 99942 Apophis Size: 300 meters Probabilty of Collision in 2036: 1 in 45,000 (as of last year) 2029 Orbit-changing encounter

13. Factors important in asteroid collisions Planetary Gravity g planet = 9.8 m/s

14. Target Density Rocky Crust: ρ = 2700 kg/m 3 (Water: ρ = 1000 kg/m 3 )

15. Impactor Density Density: ρ = 3000 kg/m 3 max Comet: ρ = 300-700 kg/m 3

16. Kinetic Energy KE = ½mv 2 v meteor = 10 - 40 km/s (assume 30) Angle of Impact Most common: 45°

17. Equation for Radius of Impactor from De Pater and Lissauer (2001) R meteor = 0.401( ρ planet ) 0.42 (D crater ) 1.28 (v meteor ) 0.56 (g planet ) 0.28 ( ρ meteor ) 0.42 (2700) 0.42 (9.805) 0.28 (3000) 0.42 (30000) 0.56 2.26 × 10 -3