CEN 511: Recemt Discoveries in Astronomy

1. What scientific advance in the field of biology, which took place at the same time that Darwin and Wallace were formulating their ideas about evolution but was unknown to them, would have greatly assisted them in understanding natural selection?
2. Which geologist argued eloquently for the concept of uniformitarianism and heavily influenced Darwin's ideas?
3. Which geologist argued for catastrophism? What sorts of evidence did he put forward in favor of his ideas? Why do you think his arguments failed to persuade most scientists?
4. Briefly summarize the major evidence supporting asteroidal or cometary impacts as the driving force causing the Cretacious/Tertiary extinction.
5. Estimate the volume of a 10 km diameter spherical asteroid. If this volume was spread in a uniformly thick layer over the entire surface of the Earth, how thick would the layer be? Given this result, why is the actual thickness of the Cretacious/Tertiary layer about 100 times thicker?
6. Why does an impact of an asteroid on the Earth create a more energetic event than the impact of the same object on the Moon?
7. What recent (last 10 - 15 years) event occurring in our solar system graphically showed the enormous consequences of impacts?
8. Why does an asteroidal impact always produce a circular crater, irrespective of the angle of impact? Note that all craters on the Moon are circular, but could not possibly have all been produced from impacts coming from directly overhead.