Due: in class on February 14, 2008
In this assignment, you will make rough estimates of the rate of cratering on the Earth; solarviews.com/eng/tercrate.htm is a nice reference for Terrestrial impact craters.
1. Fill in the following table using the crater list found on the site Views of the Solar System; http://solarviews.com/eng/crater.htm (the link found on the site solarviews.com/eng/tercrate.htm above).
Crater Size |
Number of Craters |
Date of the Earliest Crater |
Average Cratering Rate |
D > 150 km |
craters |
yrs ago |
per My |
150 km > D > 100 km |
craters |
yrs ago |
per My |
100 km > D > 50 km |
craters |
yrs ago |
per My |
50 km > D > 10 km |
craters |
yrs ago |
per My |
10 km > D > 1 km |
craters |
yrs ago |
per My |
D < 1 km |
craters |
yrs ago |
per My |
Note--In the above table My stands for million years
How accurate are your derived cratering rates? What are the possible sources
of error in your estimate?
[that is, Do you think you are counting all of the
impacts over the last few billion years? Why or why not.]
2. Roughly, how often do we suffer big hits? ____________________________ Define a big hit as an event that produces a crater with diameter larger than 50 km. Roughly, when was the last big hit? __________________________________ Note that the Chicxulub crater, the purported dinosaur killer left a crater ~ 170 km in diameter.