Project Goal: To observe the changing altitude and azimuth of the Sun throughout the year.
What You Need for This Project
To do this project you will have to be able to view the movie clip included with this project. All Macs come with a version of QuickTime and computers running Windows have a movie viewer called Media Player. The movie clip should play using either type of computer or player.
If your computer does not have QuickTime movie viewer installed you can download the Macintosh or Windows version from the internet by clicking on QuickTime. Also, an installable version of QuickTime is included on the StarryNight CD program disk.
Start the movie and watch as Sirius rises and sets. Drag the horizontal scroll box to the left to rewind to the first frame of the movie. Clicking once to the right of the scroll box will advance to the next time frame. Alternately, if you are using a QuickTime viewer, you can click the right arrow at the end of the scroll bar. Each click advances one time frame forward. The left arrow allows you to step backward in time.
What You Need to Know for This Project
In the upper left hand corner of the movie screen you will see the date (March 21, 2000) and time (12 noon), as well as the altitude, azimuth, right ascension, and declination of the Sun. This data updates every 2 days for one year as the movie runs.
Record the date and corresponding altitude, azimuth, right ascension, and declination of the Sun. begining March 21, 2000 A.D. and ending March 22, 2001.A.D,
The Sun's noon (upper transit) altitude = 90deg - Latitude + The Sun's declination.
For a discussion of relavent information see Voyage 2, Voyage 4, Voyage 6.
To begin your observations click The Sun's Yearly Motion
Print or copy the Project Results Form on which to record you answers and hand it in to your instructor.
Results Form
Name____________________ Student Number__________ Class ______________
Date ____________________
Task 1: Observing the Sun"s yearly motion.
Time of Observations___________________
Latitude_____________ Longitude________________
Date Altitude Azimuth Right Ascension Declination
March 21, 2000 _____________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
June 21, 2000_______________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
September 21 2000__________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
March 21, 2001_____________________________________________________________________________
Task 2: Plot the Sun's altitude on the vertical axis of a graph and azimuth on the horizontal axis.
Hint: Because the Sun"s azimuth remains around 180 degrees, the best units for the azimuth axis might possibly be in minutes of arc. There are 60 minutes of arc in 1 degree.
Based on your observations:
1. Describe how the Sun's altitude varies throughout the year.
2. On what date is the Sun's altitude largest?___________________.
3. On what date is the Sun's altitude smallest?___________________
4. The Sun's noon altitude on March 21, 2000 A.D. was__________________. Is this value what you would predict using the relationship,
The Sun's noon (upper transit) altitude = 90deg - Latitude + The Sun's declination.
Predicted value:_____________________.
5. Compare the Sun's noon altitude on December 21, 2000 A.D. with the predicted value.
Observed Value______________________
Predicted value:_____________________.
6. Complete the following table based on your observations,
Sun"s Noon
Right Ascension Declination Altitude Azimuth
Vernal Ewuinox (March 21) __________________________________________________
Summer Solstice (June 21) __________________________________________________
Autumnal Equinox (Sept 21) __________________________________________________
Winter Solstice (December 21) __________________________________________________