Thanks for making this series of posts. What technology is used to determine the polarity of a sunspot?
Really enjoy this info. I'm about the most undisciplined amateur EVER, but I try really hard never to miss an episode. SO informative.
Great information for Amateur Radio propagation. It looks like cycle may have started. Keep up the good work.
After a bit of digging, I can answer my own question, info on the instrumentation used in modern times would still be interesting to hear about. From: https://en.wikipedia.org/wiki/George_Ellery_Hale "In 1908, he used the Zeeman effect with a modified spectroheliograph to establish that sunspots were magnetic. Subsequent work demonstrated a strong tendency for east-west alignment of magnetic polarities in sunspots, with mirror symmetry across the solar equator; and that the polarity in each hemisphere switched orientation from one sunspot cycle to the next." A more broad-scope article on sunspots: https://en.wikipedia.org/wiki/Sunspot mentioned another interesting characteristic of sunspots. "Early in the cycle, sunspots appear in the higher latitudes and then move towards the equator as the cycle approaches maximum, following Spörer's law." Also, see: https://en.wikipedia.org/wiki/Zeeman_effect
