Astronomy midterm question: telling "Moon-time"

Astronomy 210 Midterm 1, Fall Semester 2008
Cuesta College, San Luis Obispo, CA

[20 points.] Shown at right is an excerpt from a comic strip* printed on March 23, 2008. Discuss what hour it is if the Moon is highest overhead with this phase, using a diagram showing the positions of the Sun, Moon, and Earth.

*The Family Circus, Bill Keane, ©King Features Syndicate, Inc.

Solution and grading rubric:

• p = 20/20:
  Correct. Phase as shown is waning crescent, which is highest overhead at 9 AM (rises at 3 AM, and sets at 3 PM). Explanation includes a complete Sun-Moon-Earth diagram.
  
• r = 16/20:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. Diagram is correct, but time is wrong.
  
• t = 12/20:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors. At least has a serious attempt at a Sun-Moon-Earth diagram.
  
• v = 8/20:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. May involve lunar eclipses.
  
• x = 4/20:
  Implementation/application of ideas, but credit given for effort rather than merit.
  
• y = 2/20:
  Irrelevant discussion/effectively blank.
  
• z = 0/20:
  Blank.
  

Grading distribution:
Section 70158
p: 36 students
r: 7 students
t: 21 students
v: 13 student
x: 0 students
y: 1 student
z: 0 students

A sample "p" response (from student 1616):