Solar Flares and Auroras

Introduction

Our sun is a dynamic star. While you swim at the beach on a warm, sunny, summer day, you enjoy what seems to be a steady unchanging supply of light from the sun. The truth is, even while you are at the beach, events are unfolding on the sun that can cause dramatic changes here on Earth. The plasma of the sun’s surface is constantly churning, arching prominences and immense towers forming as magnetic fields twist and flex. These features go unnoticed by the human eye yet when magnetic field lines break can cause impacts we see and feel here on our planet.

A sudden eruption of light and plasma from the sun, caused when magnetic field lines break and reconnect, are called solar flares. Sometimes, this material can reach the Earth and trigger the geomagnetic disturbance we see in our night sky as the aurora. Solar flares are ranked – based on the amounts of X-ray and UV radiation they emit. The classes of solar flare – from strongest to weakest – are X, M, C. B. and A. In this activity, you will be looking for any patterns in the numbers of X and M class flares from 1975 - 2016 by using Google Sheets to construct a scatter plot of year versus number of M and X class flares.

Procedure

The table below consists of data compiled from the Solar Flares page of the NOAA National Centers for Environmental Information website. The Solar Flare Index was “data mined” to find the total number of M and X class flares over the 41 year period from 1975 to 2016. Table 1 is missing data for 6 years – 1977, 1987, 1988, 1991, 1996, and 1998. You will do some data mining to obtain the missing data.

  1. Go to this URL: From Solar H-alpha Flare patrol observations worldwideclickDownload Data. It will take you to a new page.
  2. On the new page, under Parent Directory, click the goes/ link. This will take you to a new page.
  3. On the new page, under Parent Directory, click the xrs/ link.
  4. You will see a listing of links for solar flare data starting with 1975 and ending with 2016. Right click on the file for 1977 and download it to your computer.
  5. Open Excel.
  6. Import your txt file of solar flare data from 1977. On the import menu, choose the Text file option. Choose Fixed width, then click Finish.
  7. Your data will appear on your Excel workbook. Sort it based on the solar flare class. Find the column of data that consists of the single letters A, B, C, M, and X. This is the column for solar flare class. Sort the data based on this column.
  8. Delete all rows containing A, B, and C.
  9. Count the number of M class flares and the number of X class flares.
  10. Enter the total number of M and X class flares in Table 1 for 1977.
  11. Repeat this process for the other years.
  12. Use Google Sheets to generate a scatter plot of year versus number of M and X class flares.

Table 1: Number of M & X Class Flares – 1975 to 2016

Year / Total M and X Class Flares / Year / Total M and X Class Flares / Year / Total M and X Class Flares
1975 / 2 / 1989 / 679 / 2003 / 180
1976 / 15 / 1990 / 289 / 2004 / 134
1977 / 1991 / 2005 / 121
1978 / 195 / 1992 / 212 / 2006 / 18
1979 / 289 / 1993 / 74 / 2007 / 10
1980 / 406 / 1994 / 25 / 2008 / 1
1981 / 520 / 1995 / 11 / 2009 / 0
1982 / 596 / 1996 / 2010 / 23
1983 / 112 / 1997 / 24 / 2011 / 119
1984 / 121 / 1998 / 2012 / 130
1985 / 16 / 1999 / 174 / 2013 / 111
1986 / 22 / 2000 / 232 / 2014 / 221
1987 / 2001 / 331 / 2015 / 119
1988 / 2002 / 231 / 2016 / 16

Graph Analysis

  1. How do the number of M and X class solar flares vary over time? Is there a pattern? If so, describe it.

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  1. Sunspots are cooler region in the photosphere of the sun that appear as darker spots. These spots can be seen in visible light images of the sun. Sunspots are caused by disturbances in magnetic field lines that suppress convection of heat into the photosphere from below. Compare the graph of sunspot numbers below to your graph of solar flares. Are there any similarities? Are solar flares also caused by magnetic field disturbances? Are both solar flares and sunspots indicators of changes in the activity of our sun?

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Solar activity can cause disturbances in the Earth’s magnetic field. The constant release of charged particles form the sun, known as the solar wind, carries its own magnetic field. This field interacts with Earth’s own geomagnetic field. Higher energy eruptions from the sun, including solar flares and coronal mass ejections can cause a greater level of disturbance, often resulting in geomagnetic storms.

The level of disturbance in the geomagnetic field is measured using the Kp Index. This index is essentially an average of the amount of disturbance in the horizontal component of the magnetic field over a global network of ground-based magnetometers. The Kp index consists of 10 values, with 0 indicating little disturbance in the Earth’s field and 9 indicating a high level of geomagnetic “storminess”.

The graph below shows the number of days that Kp was 5 or higher over a 23-year period (1994-2017). Data comes from archival records at the NOAA Space Weather Prediction Center.

Graph Analysis

  1. What pattern can you see in the number of days Kp is 5 or higher? Is the pattern similar to that seen in either your graph of Table 1 or the graph of annual sunspot number?

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Going Further

Scientists claim that magnetic disruptions on the sun lead to disturbances in Earth’s magnetic field, and that these disturbances can have impacts on our technology. How does the data you have explored support this claim?

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NGSS Storyline Unit: How Could a Carrington Event Level Solar Flare Affect us Today?