So Constant And Unspotted Didst Thou Seem1
Guest essay by David Archibald
The image of the Sun today is spotless.
This is the first spotless day of the 24-25 solar minimum. Not a great deal can be read from that. According to Wilson, for cycles 9-14, sunspot minimum followed the first spotless day by about 72 months, having a range of 62-82 months; for cycles 15-21, sunspot minimum followed the first spotless day by about 35 months, having a range of 27-40 months. So we could still be six years from minimum making Solar Cycle 24 about 13 years long. Longer is weaker in the following cycle, and colder.
When the Sun goes blank we still have what the professionals use – the F10.7 flux:
Figure 1: F10.7 Flux 2014 – 2016
Figure 1 shows that the F10.7 flux has been in a couple of parallel downtrends since early 2015…
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