This one is a lot more complicated – and there is a lot more verbaige at the two links. These are https://judithcurry.com/2023/09/01/geophysical-consequences-of-celestial-mechanics/ … the post is by Vincent Courtillot, Jean Louis Le Mouel, and Fernando Lopes, scientists based in France. It begins by saying they have connections to the geomagmetics department of the Institut de Physique du Globe de Paris and they have retained an interest in solar-terrestrial relationships. Being in charge of geophysical observatories they have paid attention to a long series of observations which they have analysed. Some 24 articles have been published over the last 5 years, which are listed by Judith, one by one. The research includes sunspot numbers – and variation from solar cycle to solar cycle. Anyone interested in this research will find this link interesting.
The comments are also interesting as it is a science based web site which attracts science informed people. Basically, there are a lot of unknowns – what we can mostly take from the link. These include centennial solar cycles and the role of the planets, such as Jupiter and Saturn, Uranus and Neptune. Then we have an unknown when it comes to galactic radiation, the earth’s geomagnetic field, and earth’s shifting crust [tectonics] as well as volcanic eruptions. On top of that the occasional bolide. The positions of the major planets affects changes in the position of the centre of rotation of the entire solar system, and the angular momentum of the sun. Newton’s law of gravitation makes clear which planets are troublesome.
The second link, at https://www.wattsupwiththat.com/2023/09/02/geophysical-consequences-of-celestial-mechanics/ … repeats Judith’s post for another audience. It is also followed by a lot of comments. These are not necessarily knowledgeable – so, beware. What the authors seem to be saying is there is not one sole mechanism that continues to produce a predictable variable effect. However, the article is not only about predicting sun spot cycles but the geophysical effects that make the solar system work. The celestial mechanics, it seems, have an effect on earth’s biosphere, from the atmosphere down to the core. Earthquakes play a role in weather, for example.
Some other useful links – https://nap.nationalacademies.org/read/6238/chapter/10 .. and the Gleissberg cycle – roughly 90 years [but variable].