IT CAME FROM

Asteroids, comets, and YOU

Formation of the Solar

System

Formation of the

Moon

Luna

The Asteroid Belt is not like

this

Chicxulub

65 million years ago

180 km wide

Barringer Meteor Crater (Arizona)

49,000 years ago

1.186 km diameter (0.737 miles)

Area surrounding the 1908 Tunguska Event, circa 1927

Artist’s Conception, just before impact

When will the next collision occur?

Asteroid 99942 Apophis

Size: 300 meters

Probabilty of Collision in 2036: 1 in 45,000

(as of last year)

2029 Orbit-changing encounter

Factors important in asteroid collisionsPlanetary

Gravity gplanet =

9.8 m/s

Target DensityRocky Crust: ρ = 2700 kg/m3

(Water: ρ = 1000 kg/m3)

Impactor DensityDensity: ρ = 3000 kg/m3 maxComet: ρ = 300-700 kg/m3

Kinetic EnergyKE = ½mv2

vmeteor = 10 - 40 km/s (assume 30)

Angle of ImpactMost common: 45°

Equation for Radius of Impactorfrom De Pater and Lissauer (2001)

Rmeteor

=

0.401 (ρplanet)0.4

2

(Dcrater)1.2

8(vmeteor)0.5

6

(gplanet)0.2

8(ρmeteor)0.4

2

(2700)0.4

2

(9.805)0.

28(3000)0.4

2

(30000)0.

56

2.26×10-3