According to what we know so far, if the motion of planets is affecting solar variability as the myriad correlations which have been discovered suggest they are, then it must be via one or a combination of the known forces: Gravitation, Tides, Electromagnetism.
Because our knowledge is so incomplete, the safe way to proceed is to not rule out any of these possibilities, but to investigate, compare observations, make some logical deductions and inferences, and draw up some tentative hypotheses.
Since it is topical, I’ll concentrate on Jupiter and Saturn in this post. In an earlier post, and in Nicola Scafetta’s paper currently under discussion, it has been shown that the periods around the solar cycle length apparent in spectral analysis of the sunspot record closely match periods related to these gas giants. This makes immediate sense, they are the two biggest planets in the solar system. But although they have the biggest and second biggest effect on the Sun gravitationally, in terms of tidal strength, Jupiter is way more powerful than Saturn, and Saturn’s tidal force on the Sun is much smaller than Venus Earth, and even tiny Mercury, as Ian Wilson showed recently.
Both Jupiter and Saturn (and Earth) display strong auroral lights near their poles. This is an indication that strong interactions are occurring between the Sun and these planets. If electro-magnetism is important in the proposed planetary effects on the Sun, we should be able to find other evidence which indicates this.
Our old friend Vukcevic made an interesting discovery some time ago. He looked at the separation angle between Jupiter and Saturn at solar cycle minimum two ways. The first was the simple geometrical angle made in space. the second was he called ‘the magnetospheric angle’ (I think I would call it the helio-magnetic angle), which he measured along the Parker Spiral, which is the spiral of differentiation in the flow of the varying strength of the solar wind relative to the stellar background. It is spiral because it moves outwards as the Sun spins on its axis. This revealed something very interesting, as the two plots below show.
As you can see, the second plot, measuring angles along the Parker Spiral, is much more coherent and regular, demonstrating a potential relationship between the relative positions of Jupiter and Saturn, and the occurrence of Solar cycle minimum, which is electromagnetic in nature.
This inference is supported by an investigation I made independently of Vuk’s work (which I didn’t know about at the time), looking at the Jupiter – Earth – Venus cycle using Roy Martins alignment model. Roy’s model contained weighting for the influence of the planets, which he had set up for tidal influence. I adjusted these values, reducing Venus’ influence as it has very little magnetosphere of its own, and setting the angles between planets to lie along the Parker Spiral instead of in straight geometrical lines. The result was startling, and improved further when I adjusted the output data to account for variation in solar wind-speed. I used Leif Svalgaard’s reconstruction, extended further back in time with that of Rangarajan and Baretto.
It seems that as well as Jupiter and Saturn, Jupiter and Earth have a lot to do with the timing of solar cycles and their profile, although amplitude is clearly another matter, perhaps being affected by the same planets in a different way, or by other planets through other fundamental forces.
All in all, I’m inclined to the view that the timing of solar cycles is being modulated more strongly by electromagnetic forces than by tides or gravity. What is also clear from the data I have studied, is that this relationship gets strained when other planetary factors occasionally impose, as at the onset of the Dalton minimum, and perhaps around now, around one de Vries cycle later. That’s for another thread.