Name: 

Astronomy 3 - Problem Set 9

1. Based on the information given in Figure 12.25, can you estimate
   the probability of any individual person being killed by a mass
   extinction event in his/her life time.  How does that probability
   compare withe probability of a fatal airline accident ?

2. how are continents built up? describe a few of the processes that
   have shaped North America.

3. If life is based on information, what is that information?

4. What is the difference between chemical evolution and biological evolution?

5. Based on the information given in Figure 9.45, ie South American
   and African continents started to drift apart 120 million years
   ago, can you estimate the speed at which they are separating.  How
   does it compare with the crawling speed of a banana slug?

6, As the Sun gradually brightens in the future, how can the CO2 cycle
  respond to reduce the warming effect?  Which parts of the cycle will
  be affected?  Is this an example of a positive or negative feedback?

7. why does the energy produced by fusion in the solar core take so
   long to reach the solar surface?  Describe the processes of
   radiative diffusion and convection in the solar interior.

8. Use the fact that each cycle of the proton-proton chain converts
   4.7 x 10^-29 kg of mass into energy, along with the fact that the Sun
   loses a total of about 4.2 x 10^9 kg of mass each second, calculate
   the total number of times the proton-proton chain occurs each second
   in the Sun.  Compare quantitatively the amount of mass loss during the
   entire life of the Sun with its present total mass.

9. The star 51 Pegasi has about the same mass as out Sun.  A planet
   discovered around it has an orbital period of 4.23 days.  The mass
   of the planet is estimated to be 0.6 times the mass of Jupiter.
   Use Kepler's third law to find the planet's average distance from
   the star.  What is the orbital speed of this planet?  What is the 
   speed of 51 Pegasi's reflex motion?


10. Based on the Drake equation on p725 of the textbook, estimate the
    number of communicative civilizations per galaxy from your own
    estimates of the factors.