Astronomy 201
Summer 1996
Sullivan / Beck-Winchatz

Quiz #3 (08/01/96)

    1. Explain the greenhouse effect.
    2. Name 2 greenhouse gases that are important on the Earth. If Earth had no greenhouse effect, would there be significant consequences for life?
    3. The atmosphere of Mars has a much higher percentage of carbon dioxide than the Earth's atmosphere does. Yet the greenhouse effect there is much weaker - why?
    4. There is a similar amount of carbon dioxide on Earth as on Venus. For each of these planets, state the form in which we mainly find the CO2 today, and explain in detail why it is in this form.

    1. Why do we think that water once existed in liquid form on Mars?
    2. What does this imply for the former atmosphere of Mars?

  3. There is virtually no solid, liquid, or gaseous water on Venus.
    1. Has this always been the case? How does the abundance of HDO ("heavy water") in Venus's atmosphere help answer this question?
    2. Depending on your answer to a., explain why there has never been any water on Venus or how Venus lost its water.

  4. The first row of the following table contains four distances from the Sun. For each of these distances, choose the planet (or lack thereof) which is found at this distance (row two), the temperature of the solar nebula at the time of formation of the planets (row three), and the molecule / mineral that condensed at this temperature (but not at slightly higher temperatures) (row four).

    Distance 0.2 A.U. 1 A.U. 1.5 A.U. 5.0 A.U.
    Planet Mars None Jupiter Earth
    Temperature450 K 175 K 1900 K 600 K
    molecule/mineral iron oxide gases only silicate minerals water

  5. In the past 9 months, half a dozen planets orbiting stars other than the Sun have been discovered.
    1. Describe the observational method used for these discoveries.
    2. Explain how the newly discovered planets confirm or do not confirm our current theories about the formation of planetary systems.
    3. Do you think this sample of planets is representative of all planetary systems? Explain!

  6. Many scientists believe that the existence of our Moon and Jupiter were important for the evolution of life on Earth.
    1. Explain why this may be the case.
    2. It is also believed that Jupiter may have prevented the emergence of life on Mars. How could this have been accomplished?

  7. Despite the fact that helium is 10% of all atoms in the Universe, there is extremely little in the earth's atmosphere. Why?

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