SUNSPOTSWesley Toler

NOTES

"Sunspot TRACE". Licensed under Public domain via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Sunspot_TRACE.jpeg#mediaviewer/File:Sunspot_TRACE.jpeg

WHAT ARE SUNSPOTS?

• Regions of cooler gas on the Sun’s surface

• Likely caused by fluctuations in magnetic field

NOTES

• Sunspots are regions of the sun that are cooler than the rest of the surface of the sun. The commonly-accepted theory, first posed in 1961 by H. Babcock, is that variations in the sun’s magnetic field prevent the sun’s surface from being heated equally, leaving some portions cooler (and darker) than the rest.

Sunspots often form in pairs, with one having a positive magnetic orientation and the other having a negative magnetic orientation.

• "Sun projection with spotting-scope". Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons - http://commons.wikimedia.org/wiki/File:Sun_projection_with_spotting-scope.jpg#mediaviewer/File:Sun_projection_with_spotting-scope.jpg

NOTES

• All right, let’s look at some sunspot data. A table containing average daily sunspot numbers per month, from January 1749 to August 2014, can be accessed at http://solarscience.msfc.nasa.gov/greenwch/spot_num.txt

After removing the metadata from this file, we can load this dataset into Matlab and produce a graph of sunspot activity over this region.

NOTES

• The data on the two previous slides was collected by several groups of researchers over a period of about 265 years, tracking the average daily sunspot count per month. (The reason for choosing this type of average is likely because sunspot duration is so variable; instead of counting sunspots and keeping track of their duration, this method provides an easy way to describe the overall activity.) One can see by glancing at these graphs that the sunspot activity may not be on just an 11-year cycle; there also appears to be a rise and fall in the peaks of the 11-year cycles, suggesting another cyclical process.

• Stylistic choices: I chose to graph the sunspot numbers and standard deviation on the same graph, so I graphed them with contrasting colors. I wanted to be able to look at the data closer up without zooming, so I split the 256-year graph into two smaller graphs with equal axes.

NOTES

• All right, next time we will take the data that we have and split it into the 11-year cycles, and see what we can say about the larger cycle that appears to exists.

• Note: I had plans to analyze this data further, but my VCL session timed out and I lost my code. I spent most of my time researching ways to normalize the data where the axes would be equal on both images. Had I more time, I would liked to analyze the averages of each 11-year cycle, the maxes of each cycle, etc., to try to find a larger pattern.

REFERENCES

• Below are websites that I used to get some general knowledge of sunspots:

• http://www.rmg.co.uk/explore/astronomy-and-time/astronomy-facts/solar-system/sunspots

• http://en.wikipedia.org/wiki/Solar_cycle