## 20150315

### Astronomy midterm question: "midnight clear" moon inscription?

Astronomy 210 Midterm 1, spring semester 2015
Cuesta College, San Luis Obispo, CA

The image at right posted by REI[*] depicts the moon at night, with the inscription "Midnight Clear." Discuss whether or not this "midnight" inscription and moon image is plausible, and how you know this. Support your answer using a diagram showing the positions of the sun, the moon, Earth, and an observer on Earth.

[*] Daniel Bear Hunley, blog.rei.com/social/hand-lettering-art-mobile-wallpaper-beauty-go/.

• p:
Correct. The waning crescent moon (less than the left half of the moon is lit up) is highest overhead at 9:00 AM, and would have risen six hours before at 3:00 AM, such that it would be impossible to see at midnight. (May identify the moon as third quarter (highest overhead at 6:00 AM, which would rise at midnight), and may argue that the moon is either visible or not visible at midnight.) Complete diagram and reasoning.
• r:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. Diagram and/or explanation has minor errors.
• t:
Contains right ideas, but discussion is unclear/incomplete or contains major errors. Problems with either diagram or discussion.
• v:
Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Diagram and discussion problematic.
• x:
Implementation/application of ideas, but credit given for effort rather than merit.
• y:
Irrelevant discussion/effectively blank.
• z:
Blank.
Section 30674
Exam code: midterm01nR31
p: 23 students
r: 3 student
t: 6 students
v: 5 students
x: 1 student
y: 0 students
z: 0 students

A sample "p" response (from student 9507), arguing why this waning crescent moon picture would not be possible:

A sample "p" response (from student 7606), arguing why this third quarter moon picture could be possible:

A sample "p" response (from student 4294), discussing the impossibility of both third quarter and waning crescent moon interpretations of this photo: