Sun Journal

You will need the following equipment:

• Pencil and paper for recording your observations.
• A large sheet of blank paper for making a careful sketch, or a camera and the ability to print a fairly large (8x10) photograph.
• A magnetic compass.
• A watch to record the time of your observations.

• Choose to observe either the rising Sun or the setting Sun for this project; don't switch from one to the other.
• You must observe the Sun from the same location each time. Your location must offer a reasonably clear view of the horizon where the sun rises or sets. Trees, buildings, and mountains along the horizon are all fine, as long as these are reasonably far away.
• Before beginning your observations, make a careful sketch or photograph of the horizon from your chosen observing location. The sketch or photograph should be centered slightly south of due east if you are observing the rising Sun, or centered slightly south of due west if you are observing the setting Sun. The sketch or photo should span an angle of at least 40° horizontally, taking in the entire range of sunrise or sunset locations that you expect to see over the next two months.
• Once each week, observe the location of the Sun when it is on the horizon--immediately after sunrise or immediately before sunset. On your horizon sketch or photograph, carefully mark the Sun's location, and record the time and date. Also use your compass and outstetched hands or fists to carefully measure the angle between the sun's location and one of the cardinal directions (due east or due west), and record this angle. If the sun crosses due east or due west during the course of your observations, use negative numbers to indicate angles on the other side. (If you don't know how to use a compass to find due east or west, ask your instructor or someone else to show you. Be sure to take into account that from northern Utah, magnetic north is 14° east of true north.)
• If you can, try to take a photograph of the sun at the same time that you make each of your observations. Don't rely completely on photographs, though, because it's hard to take good photographs of the sun.
• If weather interferes with your observations on any given day, do the observation on the next possible clear day. (Thin clouds are ok, though, as long as you can determine the sun's location accurately.)
• Your observations must span at least 2 months, and must have a minimum of 6 observations of the Sun (about 1 observation per week, barring interference from weather).

• A data table summarizing all your observations.
• Copies of any photographs that you took.
• A graph plotting the angular location of the sun on the vertical axis, and the day of the observing project on the horizontal axis. Mark each of your data points, and draw a smooth line or curve that follows the data as closely as possible. You may plot the graph on a computer if you like (e.g. with a spreadsheet program), but you should still draw the smooth line or curve by hand.
• Another graph plotting the time of sunset/sunrise on the vertical axis, and the day of the project on the horizontal axis. (If your observations span the transition to/from daylight savings time, then these times should be adjusted so they are all standard time.)
• From your graphs, predict the position and time of sunset/sunrise on commencement day.
• Discuss your results in some detail, being sure to answer the following questions: Is the Sun's position on the horizon changing by a constant amount each day? Is the time of the sunset changing by a constant amount each day? Why is it important that the observations be made from the same location each time?
• Be sure to follow the general instructions applicable to all projects.