Asteroids, Comets and NEOs (Answers) Author: Sarah Roberts
Asteroids, Comets and NEOs - Impact craters on the Earth 1. Using the data given below for real impact craters on the Earth, investigate the effect of such impacts on our planet: Chicxulub, Mexico of Diameter of Earth (land Earth (water) rock 17.5km 20km/s 11.3 magnitude earthquake Dust in the Earth s atmosphere will block sunlight, causing mass extinction. rock 17.5km 20km/s There will be massive tidal waves, and dust in the Earth s atmosphere will block sunlight, causing mass extinction. Earth (land of Meteor Crater, USA Diameter of iron 50m 20km/s 6.5 magnitude earthquake Earth (water) iron 50m 20km/s Massive tidal waves. Page 2 of 5
Asteroids, Comets and NEOs - Ries Crater, Germany of Diameter of Earth (land rock 1500m 20km/s 9.1 magnitude earthquake Earth (water) rock 1500m 20km/s Massive tidal waves. 2. a) The Chicxulub Crater was formed by a rock impactor (density =2700 kg/m 3 ) with a diameter of 17.5km. Calculate the volume of the impactor, assuming it was spherical. r= 17.5 103 2 m = 8750m Volume = 4 3 π(8750)3 = 2.81 10 12 m 3 b) Calculate the mass of the impactor which created the Chicxulub Crater. Mass = 2.81 10 12 2700 = 7.6 10 15 kg c) Finally, calculate how much Kinetic Energy was released in the impact, given that it was travelling at 20km/s. KE = 1 2 (7.58 1015 )(20 10 3 ) 2 KE = 1.52 10 24 J Page 3 of 5
3. Repeat question 2 (a)-(c) for the Meteor (iron impactor, 8000kg/m 3 ) and Ries Crater Impacts also. Which impact released the most amount of kinetic energy? Meteor Crater Volume = 4 3 π(25)3 Volume = 65.4 10 3 m 3 Asteroids, Comets and NEOs - Mass = 8000 65.4 10 3 Mass = 5.2 10 8 kg KE = 1 2 (5.2 108 )(20 10 3 ) 2 KE = 1.0 10 17 J Ries Crater Volume = 4 3 π(750)3 Volume = 1.77 10 9 m 3 Mass = 2700 1.77 10 9 Mass = 4.77 10 12 kg KE = 1 2 (4.77 1012 )(20 10 3 ) 2 KE = 9.5 10 20 J Page 4 of 5
Asteroids, Comets and NEOs - The impact which caused the Chicxulub crater released the most kinetic energy - 1600 times more than the impact which caused the Ries Crater, and over 15 million times more than the impact which caused the Meteor crater. Impact craters in the Solar System 1. Investigate the effect that an impactor similar to the one which caused the meteor crater in USA (iron impactor with diameter 50m and velocity of 20km/s), would have on the other planets in the Solar System. Solar System Body Mercury Venus Moon Mars Jupiter Saturn Uranus Neptune Pluto bowl-shaped crater. Occurs approx. once every 2600 This would result in a shooting star in the sky of Venus. Occurs approx. once every 510 bowl-shaped crater. Occurs approx. once every 11,000 bowl-shaped crater. Occurs approx. once every 3500 velocity of Jupiter is 59.6km/s, hence any object would be velocity of Saturn is 35.5km/s, hence any object would be velocity of Uranus is 21.3km/s, hence any object would be velocity of Neptune is 23.5km/s, hence any object would be The highest speed that a meteor could hit a planet would be if there was a head-on collsion, However, for this to happen, the meteor would have to be travelling along the same orbital path as the planet, for which there s a maximum speed. For Pluto, the maximum velocity for impact to occur therefore would be around 11.4km/s. Page 5 of 5