Astronomy 100

Section 2, Fall 2008

Homework F

Answers

1. We can measure the age of Venus's surface from
b) the number of craters (since the impact rate can be estimated)

2. Which body has the largest iron core relative to its mass?
a) Mercury

3. The atmospheres of Venus and Mars are dominated by
e) carbon dioxide

4. Venus's clouds are made of
d) sulfuric acid (and other acids)

5. The pressure at the bottom of Venus's atmosphere is how many times that at the bottom of Mars's atmosphere?
a) 10,000

6. Most the Earth's carbon is in its
b) crust and mantle

7. In what way is Mars similar to the Earth?
d) all the above (polar caps, seasons, rotation period (length of day)

8. The "canals" of Mars are
a) optical illusions

9. Where is most of Mars's water now?
a) in the polar caps and crust

10. Evidence that a thick atmosphere once surrounded Mars comes from
a) old river beds (It takes high atmospheric pressure to maintain liquid water)

11. The evidence for life on Mars
a) is presently weak or non-existent

12. Mars's volcanos have grown large because
d) there is little or no plate motion (that is, continental drift)

13. The visible clouds of Jupiter are made of
a) ammonia (and various hydrocarbons)

14. Jupiter and Saturn are made mostly of
c) liquid molecular hydrogen

15. The magnetic fields of Jupiter and Saturn are produced by circulation of their
c) liquid metallic hydrogen interiors

16. Io is hot and has many volcanoes because
e) of tidal flexing

17. The surfaces of Ganymede and Europa are mostly
b) water ice

18. Which satellite seems to have methane lakes?
a) Titan

19. If you doubled the mass of Saturn by adding hydrogen,
e) you would slightly increase the radius, but mostly increase the density.

20. Saturn's rings are made of
a) ice coated rocks a few centimeters to meters in diameter

21. Jupiter's average chemical composition is most like that of
b) the Sun (90 or so percent hydrogen, 10 percent helium)

22. Which planet is tilted by nearly a right angle to its orbital plane?
c) Uranus

23. Why do we believe that Uranus has a relatively larger rocky core than Saturn?
d) Uranus is small for its mass compared with Saturn

24. Neptune has "captured" which bodies?
c) Pluto and Triton (Triton into orbit as a satellite, Pluto into a 3:2 orbital period resonance, that is, Pluto goes around the Sun twice for every three Neptune orbits.)

25. What is odd about Pluto?
d) all of the above (highly tilted orbit, relatively large satellite, very eccentric orbit)