Astronomy 100

Section 2, Fall 2008

Homework E

Answers

1. A blackbody
c) absorbs all radiation that falls upon it (by definition)

2. If you double the temperature of a heated solid body, it will radiate how many times more energy?
d) 16 (radiation power from a black body depends on the fourth power of the temperature)

3. Of those listed below, a body at 5 degrees Kelvin can produce only
a) radio radiation (The others require continuously increasing temperatures.)

4. Absorption and emission lines are caused by energy changes in atomic and molecular
a) electrons

5. The age of the Sun, Earth, and Solar System are calculated to be
d) 4.5 billion years

6. We know the ages of the meteorites (asteroids that hit the Earth), hence the age of the Earth and the Solar System, from
b) the decays of radioactive elements

7. What kind of clouds do we find on the Moon?
e) none at all

8. The Moon keeps one face pointed toward
b) the Earth (the result of tidal locking)

9. How many times larger (in diameter) is the Earth than the Moon?
d) 4

10. Craters on the Moon are produced by
a) impacts by bodies from space

11. The lunar maria are
d) lava-filled impact basins

12. The Moon's water
d) may consist of a tiny bit of ice at the poles

13. Why is the Earth less heavily cratered than the Moon?
d) Various processes on Earth erode or destroy impact craters

14. The islands of Hawaii are caused by
a) a mantle plume that rises up from the core

15. The Earth's mantle is made mostly of
a) silicates

16. Continental drift is caused by
d) convection in the Earth's mantle

17. The Earth's inner core is made mostly of
a) solid iron

18. The Earth's outer core (that just beneath the mantle) is made mostly of
b) liquid iron

19. Circulation in the Earth's outer core produces the Earth's
e) magnetic field

20. Earthquakes and volcanos are ultimately produced by
d) convection in the Earth's mantle

21. The Moon has no continental drift, that is, is all one plate because
c) the Moon is small and cooled off quickly

22. Roughly how deep (in miles) is the Earth's breathable atmosphere?
b) 3

23. The Earth's breathable atmosphere is made mostly of
c) nitrogen

24. Mercury's sunward surface is hot because of
e) its proximity to the Sun

25. Venus is hot mostly because of
a) its carbon dioxide atmosphere