Solar Activity Makes Big Headlines
How accurate have sunspots been counted? How well have we recorded the 11-year sunspot cycle over the centuries? The surprising answer to that question is, not very well!
Last month had the largest monthly change in solar sunspot activity since July 2007.
October was a very busy month for solar storms linked to sunspots. They made global headlines.
Daily sunspot tallies make up the oldest continuous data series in all of science. It officially goes back to January of 1749.
Sunspots are ginormous solar magnetic storms that unleash powerful solar winds and lethal doses of radiation directly affecting Earth. Knowing how many there are is vitally important.
How accurate have sunspots been counted? How well have we recorded the 11-year sunspot cycle over the centuries?
The surprising answer to that question is, not very well!
A look at October’s daily sunspot tallies demonstrates it.
Sunspots have been meticulously counted since Galileo started the practice back in 1609, just after the telescope was invented.
Today, most normal folks find out the daily count of sunspots from NASA’s spaceweather.com.
SpaceWeather showed a huge 228 sunspot count on October 23rd, 2013.
NASA uses their own counting method, commonly called the “Boulder Sunspot Number” started back in 1951.
The problem with NASA and SpaceWeather is that their number differs radically from Belgium’s officially accepted count.
The official daily sunspot number is called the “International Sunspot Number” and is maintained by the Royal Observatory of Belgium. They took over that duty from the Zurich Observatory at it’s closure in 1981.
Responsibility for counting daily sunspots has been passed down from generation to generation starting with Rudolf Wolf who standardized counting and corrected all previous records in the 1840s.
NASA and Belgium both count the same sunspots, yet get very different results. NASA applies Wolf’s original “relative sunspot number” calculation using it’s own set of observers and telescopes different from Belgium.
This graph shows daily sunspot tallies by both NASA and Belgium for last month. They are as different as a pterodactyl from a bird.
You can clearly see that some days one group’s counts go down while the other goes up and vice versa. NASA recorded and SpaceWeather reported an amazing 228 spots on October 23rd. Belgium reported just 93. For Belgium, almost half their day counts for October were more than October 23rd. NASA’s 228 sticks up like the leaning tower of Pisa. Not good.
It’s been long known that Boulder’s counts are about 25% higher than Belgium’s. But even accounting for that, Boulder still calculates out to an October monthly sunspot number of 93 compared to Belgium’s officially accepted 85.6. That is still a big, big difference.
So who is right, NASA or Belgium?
Belgium is right, of course. Why? Because Belgium counts are right by definition.