Astronomy 201 

Homework EIGHT


  1. Assuming all other things (the amount of sunlight and the amount of light absorbed and reflected by the planet are constant, ignore seasonal effects), show that the temperature on Mars should be about 10% greater when Mars is at perihelion than at aphelion?   How does this compare to similar changes on Earth?
  2. Without a greenhouse atmosphere, the temperature on Venus should be about 297 K, yet the temperature is actually 737 K.  Using the Stefan-Boltzman law, show that the surface of Venus receives about 38 times more light (from the atmospheric greenhouse) than Venus receives from the Sun.
  3. If Mars once had 6 million cubic km of water, and if one-third of the surface of Mars was covered with an ocean of constant depth, how deep was this martian ocean?
  4. What is the importance of Venus not having a magnetic field in considering how it may have lost its water?
  5. Explain the 'smoking gun' evidence that Venus once had but lost its water.