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Exploring Sunspots

 Activity Description Activity Guide Background Resources

Part 1: Importing and Graphing the Data

• Import the data from the internet into Excel.

 To import the sunspot data into Excel: Go to the following website: ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/ SUNSPOT_NUMBERS/ Open the Yearly.plt file (near the end of the list of files) Select all the data and Copy to the clipboard. Open a new workbook in Excel. On sheet1, select columns A and Paste the data. Under the Data menu, choose Text to Columns and follow the directions on the pop-up window. You will need to insert a row at the top of the sheet in order to label the columns YEAR and SUNSPOT NUMBERS NOTE: This data set contains the yearly average sunspot numbers from 1700-1997. For the graphing part of the activity, you will only need the data from 1900-1997.
• Look at the data in tabular form.  Do you notice any patterns?

• Create a connected scatterplot of the Sunspot numbers from 1900 to 1997.

• Describe the activity of the sun over this extended period of time.  Do you notice any patterns in the graph?

• When was the largest peak?  When was the smallest peak?

Part 2: Analyzing the Cyclic Behavior

• How many years elapse between low points?  The graph of the average monthly sunspot numbers for each year shows a regular cycle of highs and lows.  To estimate the cycle’s period, we can calculate the average number of years between successive low points.  Calculate this average over at least 5 successive low points.

• Look at the graph closely.  Are the cycles symmetric? (i.e., does it take the same number of years to go from a low to a peak as it does to go from a peak to a low?)

• Based on the pattern observed in the data, in what year should the next peak in sunspot activity occur?  When should the next low occur?

Extensions:

• What other phenomena might be periodic? (Hint:  some weather related data is periodic!)  Find data for the phenomenon of interest. The home page of the National Geophysical Data Center (http://www.ngdc.noaa.gov) provides links to lots of scientific data.  Import the data into Excel and create a graph.  If the data is periodic, estimate the period.  Is the period similar to that for sunspots?

• Can you think of any phenomenon that might be related to solar activity?  Conjecture a possible phenomenon and its relationship to sunspot numbers.  Find the data of interest, import it into a spreadsheet and compare it with the sunspot data.  (The activity entitled Sunspots and Geomagnetic Disturbances will explore one such relationship in detail.)

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