Astronomy 210 Midterm 1, fall semester 2018
Cuesta College, San Luis Obispo, CA
The following description of Jupiter was given in a science magazine[*]:
At the beginning of this month Jupiter rises around midnight. At the end of this month Jupiter rises around 10 PM.
Discuss how this earlier shift of Jupiter's rising time over the course of a month would be plausible for an observer in San Luis Obispo, CA, and how you know this. Support your answer using diagrams showing the positions of the sun, Jupiter, Earth, and an observer on Earth.
[*] Astronomical Notes,"
Scientific American, vol. 43 no. 235 (July 3, 1880), p. 11,
books.google.com/books?id=6ok9AQAAIAAJ&dq.
Solution and grading rubric:
- p:
Complete diagram and reasoning includes the following
explanations for an observer on Earth looking at Jupiter:- Jupiter's position in its orbit around the sun is "ahead of" Earth's
position in its orbit around the sun such that the observer on Earth at
midnight is able to see Jupiter rising from the east horizon, and
- a few months later, Earth has "caught up" to Jupiter (but not yet at superior conjunction) such the observer on Earth will see Jupiter rising from the horizon at an earlier time.
- r:
Nearly correct (explanation weak, unclear or only nearly complete); includes extraneous/tangential information; or has minor errors. May have
Jupiter highest overhead at midnight (at superior conjunction) for the earlier
drawing, and then Earth slightly ahead of Jupiter for the later drawing such
that Jupiter is overhead at 10 PM.
- t:
Contains right ideas, but discussion is unclear/incomplete or
contains major errors. May have geocentric model of Jupiter orbiting Earth, or
Earth staying still while Jupiter moves relative to Earth around sun, or
observer/times on Earth are in wrong positions.
- v:
Limited relevant discussion of supporting evidence of at least some
merit, but in an inconsistent or unclear manner. Some attempt at diagram(s),
but no clear indication of observer/times on Earth and how relative motions of
Earth and Jupiter would cause the earlier shift of Jupiter's rising time.
- x:
Implementation/application of ideas, but credit given for effort rather than merit.
- y:
Irrelevant discussion/effectively blank.
- z:
Blank.
Grading distribution:
Section 70158
Exam code: midterm01Sa1Y
p: 7 students
r: 11 students
t: 9 students
v: 8 students
x: 1 student
y: 1 student
z: 0 students
Section 70160
Exam code: midterm01n4mR
p: 1 student
r: 3 students
t: 5 students
v: 8 students
x: 2 students
y: 0 students
z: 0 students
A sample "p" response (from student 1999)
Another sample "p" response (from student 4008)
Shown at right is a photographic montage[*] of a crescent moon just above a mountain range, with the sun higher above the mountains, off to the left of the photograph. Discuss whether this composition is plausible or implausible for an observer in San Luis Obispo, CA, given the phase and position of the moon in the sky, and the time of day. Support your answer using a diagram showing the positions of the sun, moon, Earth, and an observer on Earth. 
