Astronomy midterm question: telling "Moon-time"

Astronomy 210 Midterm 1, Fall Semester 2009
Cuesta College, San Luis Obispo, CA

[20 points.] Shown at right is an excerpt from a comic strip (Wizard of Id, Brant Parker and Johnny Hart, Creators Syndicate, June 28, 2009). Given the phase of the moon shown here, discuss a plausible time at night for the events depicted in this comic strip, using a diagram showing the positions of the sun, moon, and Earth.

Solution and grading rubric:

• p = 20/20:
  Correct. Identifies the phase as waning crescent, which is highest overhead at 9 AM (rising at 3 AM, and setting at 3 PM), using a diagram of the sun, moon, and Earth. May choose anytime between 3 AM to 6 AM (sunrise) as being a plausible time at night for the events depicted in the comic strip.
  
• r = 16/20:
  Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. May include 9 AM or any time after sunrise, or diagram has minor inconsistencies/errors.
  
• t = 12/20:
  Contains right ideas, but discussion is unclear/incomplete or contains major errors. Problems with either diagram, phase, or time.
  
• v = 8/20:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Problems with diagram, phase, and time.
  
• 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: 15 students
r: 13 students
t: 7 students
v: 19 students
x: 0 students
y: 0 students
z: 0 students

A sample "p" response (from student 4614):

A sample "r" response (from 1623), who at least finds it strange that it is apparently dark outside: