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Historical Sunspots
Keith Greiner
September 27, 2016
When Galileo first turned his telescope to the heavens in 1610, one of his first observations was of the sun. (Don’t do what he did. Don’t look at the sun through a telescope). Galileo’s notes show that 17th century icon, counted the spots on a regular basis and determined that the sun rotates on its axis. Two hundred ninety-one years later, the invention of radio by Guglielmo Marconi, and the first transatlantic transmission of radio signals in 1901 brought the realization that those signals are affected by solar conditions. High levels of solar activity can cause radio waves to bounce off the ionosphere and travel farther – all the way around the world.
Radio communication has changed in the last 115 years, and yet the influence of the sun is still a major concern. High levels of solar activity may help high frequency communication, but they may negatively affect satellite communications and the national electrical power grid. So many things are connected in some way including sunspots, coronal mass ejections, terrestrial plasma, magnetic sub-storms on earth, auroral activity, telecommunications, and the electrical power grid.
Our understanding of future solar activity is informed by the history of solar activity. Since 1749, there have been 25 peaks in solar activities. By reconstructing the historical sun spot activity, we can see the patterns of daily, monthly, annual, and multi-year solar activity. The following time series graph shows smoothed average monthly sunspots for 3,212 consecutive months.
By looking at the distribution of sunspots for all months in the historical data set, we can see the likelihood that a certain level might occur.
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