Solar Cycle 24 Review

Sunspot solar maximum Solar Cycle 25

Recently, NASA announced that they could say the sun had entered solar cycle 24, and the start of solar cycle 25. This announcement comes after the December 2019 solar minimum, which will make the start of a new solar cycle.It is worth noting that as a result of our Sun being so variable, it can take months after the fact to declare this event.

Solar Cycle 24 Review

Beginning in December 2008, Solar Cycle 24 had minimum sunspot number of 2.2. Sunspot activity was minimal until early 2010, and activity would reach maximum activity in April 2014 with a 23 month sunspot number of 81.8. 

Predictions And Results

There were two theories predicted regarding how strong Solar Cycle 24 would be, with 1 theory predicting an active cycle and the 2nd theory predicting a quiet cycle. Prior to 2006, the difference was substantial with a minority of researchers predicting the smallest cycle in recent memory.  However, there was a group of researchers, including one at NASA, predicted that it would be more intense than almost any on record.

In the end, NASA funded and used Ken Schatten’s physics-based models, which utilized a solar Dynamo model, to accurately predict the low.[1] This method used the correlation between solar magnetic field strength at solar minimum to sunspot number at solar maximum to accurately predict the peak solar flux of each of the last three solar cycles.

It turns out that not only were Schatten’s predictions become accurate as early as solar minima, 5–6 years before solar max. Nevertheless, it turns out that solar cycle 24 had a “double-peaked” maximum, with peaks in the years 2011 and 2014.

It is worth noting that the topic of the solar cycle is currently the subject of research, the models of sunspot generation

ISES Solar Cycle 24 Sunspot Number Progression. Courtesy NOAA/NASA

Major Solar Events

2014 and 2012 saw the most solar flares. Here are some of the strongest flares of the entire cycle.

  • X9.33 Flare September 6th, 2017
  • X8.2 September 10th, 2017
  • X6.9 August 9th, 2011
  • X5.4 March 7th, 2012
  • X4.9 February 25th, 2014
  • X3.19 October 24th, 2014

If you want to learn about solar minimum or solar maximum or the solar cycle, check out those articles. Keep checking back in for some more amazing content like this!


[1] = “Fair space weather for solar cycle 24” (PDF). Geophysical Research Letters, VOL. 32, L21106, doi:10.1029/2005GL024363. 2005.

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