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Ihave been following sunspot cycles for over 50 years now, starting as a teenager in the 1970s when I was a shortwave radio listener. When the sunspots are surging, some radio bands become highly active and I well remember in the sunspot maximum of 1979 that South Africans with low-power walkie-talkie CB radios were able to chat with truckers in Australia.
At other times, a solar flare will completely wipe out communication on the shortwaves and all signals fade into the noise.
However, there has never been so much confusion and speculation over what the sun is doing as there is at present. There are many models offering a wide range of predictions of solar activity. The last sunspot cycle, Cycle 24, was unusually weak, with comparatively few sunspots. These spots occur when the magnetic field of the sun breaks through the surface, causing turbulence that appears as a dark spot on the sun. The Sun’s magnetic field has generally been weakening, so this muted cycle was largely expected.
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Most predictions for the present Cycle 25 were for a similarly restrained affair, but towards the end of last year the sun roared to life, producing a range of sunspots, solar flares, coronal mass ejections and other very unusual happenings, such as a portion of the sun apparently breaking off and forming a spiral vortex around the pole. Nothing like this last event had ever been seen before. Two researchers who had predicted a stronger cycle are now saying that Cycle 25 may be peaking a year earlier than expected, in 2024. NASA researcher Robert Leamon and US National Centre for Atmospheric Research deputy director Scott McIntosh have been shaking up solar physics by looking at what they call ‘terminator events’.
The magnetic field of the Sun actually reverses as a new cycle begins. As the new cycle begins, sunspots with reversed magnetism start to appear. However, there is a point about two years after the sunspot minimum where the magnetic fields of the old and the new cycles cancel each other, and this is what is called the ‘terminator’. Leamon and McIntosh have argued that this terminator event is a much better predictor of sunspot cycles than just counting sunspot numbers.