1. Choose a location with a good view of the western horizon from which you can clearly observe the Sun at sunset. It is important that you make all of your observations from exactly the same location. Make a careful drawing of the western horizon. This drawing should be large enough to run most of the length of a standard sized sheet of paper. You should include a fairly large angular range along the horizon. You can substitute a photograph of the horizon to make your marks on. However, take that photo in the middle of the day not at sunset; make a large print (at least 5X7, 8X10 is much better) then mark the sunset positions right on the photo with a fine tip marker.
2. Optional for photographers: You may choose to photograph the setting Sun also. However, you must still mark its setting position on your sketch or horizon photo too. We have seen hundreds of bad photographs of the setting sun for this project. It is very challenging to get the exposure just right so as to see both the last tip of the Sun and the horizon clearly too.
3. Once every 4 to 6 days, indicate the position of the top of the setting Suns disk – just before it disappears – on your drawing or photograph of the horizon. Also, record the date and time of each sunset. If it is too cloudy to observe a specific sunset, then do the following days sunset instead.
4. You should record at least 7 sunsets over at least 30-40 days to complete your observing project. Two months of observing would be even better.
5. You should record the location that you made your observations from
6. Plot your data on the graph shown on the next page. On this graph, predict the location of sunset for the first day of the next week. Clearly mark that position on the graph. Using a magnetic compass to get the degrees relative to north along the horizon would be best.
7. Roughly how many degrees along the horizon has the position of the sunset moved during the course of your observations?
(Refer to https://www.youtube.com/watch?v=YMu5k3Ik7JU for suggestions of how to measure angles using your hands.) B. How much has the time of sunset changed during your study? (Remember to correctly account for daylight savings time changes.)
8. Reminder: you may supplement your chart with individual photos of sunsets, but that is not the primary data display. You must have a full page sized sketch or good sized photo of the horizon with the dates and times marked on it. One good way is to draw arrows down to the point along the horizon where the sun set, then number the arrows and include a separate data table that has the date and time for the sunset matched with the numbers for each arrow.