Observing the Sun's Position and Motion

Big Idea: Sky objects have properties, locations, and predictable patterns of movements that can be observed and described. Those motions explain such phenomena as the day, the year, the seasons, phases of the moon, and eclipses.

Goal: Students will conduct a series of inquiries about the motion of the Sun in the sky using prescribed Internet simulations and learn how the Sun follows different pathways at different times of the year.

Computer Setup:

Access http://www.heavens-above.com/ and

a) Find the CHANGE YOUR OBSERVING LOCATION link under Configuration and set your observing location and time zone. If you use the search feature, you should just be able to click "Update" at the bottom of the screen.

b) Find INTERACTIVE SKY CHART link under Astronomy. You can also use SKY CHART (OLD VERSION), but the interactive version lets you mouse over objects to see pop-up information about them. It also has a print to PDF function, which can be useful for capturing your data in the later parts of the lab.

Phase I: Exploration PART A:

1) On a map of the United States, north is toward the top of the page and west is to the left. On all of the star charts, north is toward the top of the page and west is to the right. How do you account for this difference?

2) This is the current sky. Find the YELLOW star marking the current location of the SUN. Which constellation is it closest to right now?

3) Change the time by increasing it one hour and pressing update. Exactly how has the Sun's position change on the map?

4) Slowly increase the time to later and later in the day. This system uses 24-hr "military time" or "Zulu" time. So, 6pm is actually entered as 18-hours. Determine EXACTLY what time, hours and minutes, that the Sun will set tonight. It should be the time when the Sun disappears below the western horizon (test by clicking the - button for the minutes...if the Sun reappears, then you were on the right time).

5) Which constellation was the Sun closest to when it set?

6) Is this the same or different than where the Sun was earlier in the day?

7) What generalization can you make about the relative speeds that the Sun and the stars move through the sky over the course of a day?

8) What generalization can you make about the direction the Sun and the stars move through the sky over the course of a day?

9) Describe precisely how you would test to see if this generalization is true during the night time too.

10) What is the physical cause of your generalization (what is happening physically in the world that causes what you see)?

Phase I: Exploration PART B:

When looking at the star map set for SUNSET TONIGHT:

11) on what part of the map (left, right, top, bottom or center) is the star group that appears highest in the night sky? What is the name of this star group?

12) on what part of the map (left, right, top, bottom or center) is the star group that appears near the southern horizon? What is the name of this star group?

13) on what part of the map (left, right, top, bottom or center) is the star group that appears near the eastern horizon? What is the name of this star group?

When looking at the star map set for THREE HOURS after tonight's sunset:

14) on what part of the map (left, right, top, bottom or center) is the star group that now appears highest in the night sky? What is the name of this star group?

15) Where did the stars that used to be at this position move to?

16) on what part of the map (left, right, top, bottom or center) is the star group that now appears near the southern horizon? What is the name of this star group?

17) Where did the stars that used to be at this position move to?

18) on what part of the map (left, right, top, bottom or center) is the star group that now appears near the western horizon, where the Sun sets? What is the name of this star group?

19) Where did the stars that used to be at this position move to?

20) on what part of the map (left, right, top, bottom or center) is the star group that now appears near the eastern horizon, where the Sun rises? What is the name of this star group?

21) Where did the stars that used to be at this position move to?

22) If you were to change the time to midnight, predict what would be different about the positions of the stars.

23) What generalization can you make about how the stars change position over the course of the night?

Phase II - Does the Evidence Match the Conclusion?

24) From before, precisely what time (hours and minutes) will the sun set below the western horizon tonight?

25) Using the sky chart, precisely what time the sun will set one month from now?

26) Using the sky chart, precisely what time the sun will set two months from now?

27) Using the sky chart, precisely what time the sun will set three months from now?

28) Using the sky chart, precisely what time the sun will set six months from now?

29) Using the sky chart, precisely what time the sun will set nine months from now?

30) Using the sky chart, precisely what time the sun will set twelve months from now?

31) If a student proposed a generalization that "sunset time changes about one hour per month, setting earlier and earlier in the fall and then setting later and later in the spring," would you agree, disagree with the generalization based on the evidence you collected? Explain your reasoning and provide evidence either from the above questions or from evidence you yourself generate using the star map program.

Phase III - What Conclusions Can You Draw From the Evidence?

Most of us would agree that the sun sets in the general direction of west. What conclusions and generalizations can you make from the following data collected by a student in terms of HOW DOES THE DIRECTION OF THE SUNSET CHANGE? Explain your reasoning and provide evidence to support your reasoning.

Evidence collected in standard time from

http://www.heavens-above.com/

http://aa.usno.navy.mil/data/docs/AltAz.php for Laramie,

32) Evidence-based Conclusion:

Phase IV - What Evidence Do You Need?

Imagine your team has been assigned the task of writing a news brief for your favorite news blog about how the noon-time sun's altitude above the southern horizon changes over the course of the semester. Describe precisely how and what evidence you would need to collect in order to answer the research question "How does the noon-time sun's position above the southern horizon change over the semester?" Your procedure MUST use this heavens-above.com web site, you do NOT need to use any other resources. You do not need to collect data for this phase, but you should write the instructions such that someone else could follow your instructions to successfully collect the relevant data.

33) Create a detailed, step-by-step description of evidence that needs to be collected and a complete explanation of how this could be done-not just "measure the position of the Sun," but exactly what would someone need to do, step-by-step, to accomplish this.

Phase V - Formulate a Question, Pursue Evidence, and Justify Your Conclusion

Your task is design an answerable research question, propose a plan to pursue evidence, collect data using heavens-above (or another suitable source pre-approved by your lab instructor), and create an evidence-based conclusion about some motion or position of the sun in the sky that you have not completed before. This question doesn't need to be complex. Think about the observations you've learned about so far in the lab. The best research questions are those that can't be answered by a simple yes/no, or a single number or characteristic. Look at ways you can compare/contrast or otherwise analyze a collection of data. The questions in phases II through IV are good examples. Your question can be similar, but must be different from those. If you have difficulty, ask a question in the Lab Q&A Forum or send a message to your instructor.

Research Report:

34) Specific Research Question:

35) Step-by-Step Procedure to Collect Evidence:

36) Data Table and/or Results:

37) Evidence-based Conclusion Statement:

Phase VI - Summary PRINT YOUR NAME

38) Create a 50-word summary, in your own words, that describes how the sun's motion and position changes over the day and over the year. You should cite specific evidence you have collected in your description, not describe what you have learned in class or elsewhere. Feel free to create and label sketches to illustrate your response.