Astronomy Laboratory
Sunrises and Sunsets
Is this the little girl I carried? from
Fiddler on the Roof
Is this the little boy at play?
I don’t remember growing older,
When did they?
When did she get to be a beauty?
When did he grow to be so tall?
Wasn’t it yesterday when they were small?
Sunrise sunset, sunrise, sunset,
Swiftly flow the days,
Seedlings turn overnight to sunflowers,
Blossoming even as they gaze . . .
Sunrise sunset, sunrise, sunset!
Swiftly fly the years,
One season following another,
Laden with happiness and tears . . .
One season following another,
Laden with happiness and tears . .
I. Sunrises
1. Examine what you already know about sunrises. Recall where you may have seen the Sun rise, what you’ve been taught, and think about what makes sense to you. Now, make a hypothesis. Where does the Sun rise? Does it always rise in the same location? Write your hypothesis below. (It is strongly suggested you use a pencil for this activity.)
Now, you will be lead in to conducting a scientific examination. The best way would be to observe the Sun rising yourself, but that’s not always feasible. Therefore, observations you might make on your own are provided for you.
Examine the following table.
It shows the locations of sunrises throughout the year, taken on
non-specific days in the season indicated.
|
Approximate time of year |
|
Approximate time of year |
|
|
a. Early Spring |
91.4° |
g. Early Autumn |
91.6° |
|
b. Mid Spring |
84.8° |
h. Mid Autumn |
101.3° |
|
c. Late Spring |
74.8° |
i. Late Autumn |
113.7° |
|
d. Early Summer |
61.2° |
j. Early Winter |
120.7° |
|
e. Mid Summer |
72.5° |
k. Mid Winter |
110.5° |
|
f. Late Summer |
83.9° |
l. Late Winter |
101.7° |
2. To help visually organize this data, plot these points and label them on the horizon below. Use a small sun symbol and place it right on the horizon line (the irregular line at the top of the diagram).
60° 75° 90° 105° 120°
NE E SE
3. Reflect on your hypothesis. Was it correct? How did the observational data change your ideas about sunrises? Revise your hypothesis if necessary and state it below.
4. From the table on the preceding page, what times of year does the Sun rise closest to due east? Can you infer on what two exact days the Sun rises due east? You may need to consult your textbook regarding seasons and associated specific dates.
5. From the table, when does the Sun rise furthest north and furthest south? On what exact days does this occur?
6. Reflect on how seasons affect the length of daylight hours and when these occur. Also, think about the reasons why sunrise location changes with the season. What are the primary factors influencing seasons, the length of daylight, and the path the Sun takes across the sky? Write down your ideas.
II. Sunsets
1. Based on your reasoning in number 6, infer another hypothesis. Write it below. For each of the sunrise locations, where would the corresponding sunset occur? Use the circle below to plot both sunrises and corresponding sunsets (label with lower-case letter). Assume the circle is a full 360° horizon. Use a protractor to be accurate.
0°
180°
2. Check your hypothesis at the following website:
If your hypothesis was incorrect, explain what the website provides that changes your thinking. Correct the above diagram if necessary.
3. Does part II influence your understanding of why the amount of daylight changes seasonally? If your thoughts from I.6 have changed, what do you know now?
4. Reflect on what you have learned from this laboratory. Summarize your reflections in a few sentences. In addition, consider how seasons and daylight would be different if the Earth had no tilt, or if the tilt was significantly more extreme. Explain.
Additional web resource: http://www-istp.gsfc.nasa.gov/stargaze/Ssky.htm