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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