There were two quizzes! Make sure that you check your multiple choice
answers against the correct key.
        
Quiz A
-------
   1. D.
   2. E.
   3. C.
   4. E.
   5. A.
   6. B.
   7. D.
   8. A.
   9. E.
  10. D.

Q1: The Moon Problem. With questions like these, it is best to figure
out where the Sun, Moon, and Earth are relative to one another. To an
observer on Earth the Moon just rising means that it is on the horizon
means that it is off to one side (see diagram). Which side? Imagine
how the Earth is rotating (counterclockwise) and make sure that Moon
will rise, not set! Midnight means that the Sun is straight down on
the other side of the Earth. Something like this:


        (can see all this)

------M-----E------------------- (horizon)


        (can see none of this) 






            S

a) What is the Moon's phase? Half of the Moon is always lit up by
sunlight. Convince yourself from the diagram that the observer on
Earth can see 1/2 of the lit side of the Moon and 1/2 of the dark
side. So she sees a 1/2 Moon. Convince yourself that the "curvy side"
is down (closer to the horizon).

b) The Moon appears to move across the sky mostly because of the
Earth's spin. It takes about 12 hours to rise and then set (on
average). So just 6 hours to rise to its highest point in the sky.

c) For an eclipse, we need to wait until the Earth, Moon, and Sun are
in a straight line. From the diagram, we need to wait for 1/4 of the
Moon's orbit. The Moon takes a month to go around once, so we would
have to wait a week for the next possible eclipse. Since everything
moves counterclockwise, we will have S M E in a week, so the Moon
could block the Sun which would be a solar eclipse. Remember that the
three objects only rarely line up perfectly.


Q2: Density Problem. Ice has a density of 1000kg/m^3, rock is
3000kg/m^3 and iron is 8000kg/m^3.

Planet X: 8000kg/m^3 -> This is a pure iron planet! Mix in any rock or
                        ice and the average density would be lower
                        than 8000.
                         
Planet Y: 4000kg/m^3 -> This planet is denser than rock. So it must
                        have some iron mixed in. It is mostly rock
                        with some iron. A roughly 50-50 mixture of
                        iron and ice would also work, but this is a
                        strange combination!

Planet Y: 2000kg/m^3 -> This planet is less dense than rock and more
                        dense than ice. In fact, it is midway between
                        the two! So it is 1/2 rock and 1/2 ice (like
                        Pluto).

Quiz B
-------
   1. C.
   2. B.
   3. D.
   4. E.
   5. C.
   6. C.
   7. A.
   8. B.
   9. B.
  10. C.


Q1: Same as Quiz A

Q2: Same as Quiz A