Chapter #16 The Habitability of of Planets around Other Stars.


1. What are the 3 basic requirements that a planet must have if it is to be a suitable place for life? (page 260)

2. Where (on what bodies) in our solar system are these requirements (possibly) currently met or perhaps could have been met in the past? (page 260)

3. Define the difference between the "Habitable Zone" (HZ) and the idea of the "Continuously Habitable Zone" (CHZ). (page 261)

4. If you were to use the graph in Fig 16.1 on page 262 and the information provided regarding life and liquid water on Earth from page 261, what estimate would you get for the HZ around a distant star? Express your answer in AU's. (page 262)

5. Why is the estimate you made for the HZ in part A closer and smaller that the estimates traditionally given for the HZ of our solar system. Explain your reasoning. (page 262 ; see figure caption no atmosphere)

6. In general what affect does atmospheric CO2 have on the temperature of a planet? (page 264)

7. In the absence of mechanisms to prevent the loss of atmospheric CO2, what would happen to the surface temperature of Earth and life on Earth in general? (Page 264, With a loss of CO2 the temperature of Earths surface would decrease dramatically and as a result many life forms could vanish from the Earths surface)

8. What role does plate tectonics on Earth play in the abundance of atmospheric CO2? (page 265)

9. In the absence of plate tectonics here on Earth, approximately how long would it take to remove all the CO2 from our atmosphere? (page 265)

10. What are the three possible mechanisms proposed for the loss of Mars's atmosphere? (page 266)

11. Imagine that the estimated HZ for a star extend to 1.4 AU and that a massive planet is discovered just outside the estimated HZ which has a thick atmosphere that contains a large abundance of CO2. Should this planet be considered as a possible candidate to have liquid water on it's surface? (page 268, since the planet is massive it could have captured the necessary elements for water and the presents of atmospheric CO2 would cause an increase surface temperature thus allowing for the possibility of liquid water)

12. According to Jakosky what is the estimate value (or range of values) for the inner boundary of the HZ around the Sun? (page 268-269)

13. Is Venus within the Suns HZ? (page 268)

14. As a star gets older does the HZ move closer to or farther from the star? (page 271)

15. How does the HZ for a star with less mass than the sun compare to the HZ for our sun? (page 271)

16. At what upper limit for a star's mass does it appear unlikely that life could develop? (page 271)

17. According to Figure 16.4 and the corresponding power law, how many more stars are there with a mass of .8 solar masses than there are then with masses of 8 solar masses? (page 273)

18. What two physical processes or effects can allow a Gas Giant (outside of a star's normal HZ) to have it's own HZ? (page 274)