A lot of people might visit here, see some fairly technical conversation going on, and wonder, “What’s it all about?” So I thought I’d devote a thread to explaining what we mean when we refer to ‘solar – planetary theory’. This thread is a first attempt at clearly summarizing it, and I hope a stimulating discussion will follow so that we can refine the hastily written outline presented here.
In a nutshell, it is the hypothesis that the solar system is a system in the fullest sense of the word. That is: As well as the sun having a big effect on the planets (warming them with it’s radiation, keeping them in their orbits with it’s gravity, warding off a lot of the galactic cosmic rays from entering with it’s solar wind etc), the planets also have an effect on each other, and on the sun, causing it’s complicated motion around the centre of mass of the solar system, modulating solar magnetic activity and the production of sunspots.
Issac Newton in his famous book ‘Principia Mathematica’ described the motion of the sun around the centre of mass, but held the opinion that ‘the sun feels no forces’ because according to his theory of Gravitation, the sun would be ‘in free-fall’.
So why do proponents of solar-planetary theory think the planets can affect the sun?
Firstly, Newton, although he quantified the gravitational force, didn’t try to explain what gravity was, or how it has it’s affect on matter. “I frame no hypotheses” he famously said. He lived in an age when ‘Natural Philosophy’ was trying to escape ideas which involved ‘action at a distance’. But gravity seemed to be an ‘action at a distance’ force par exellence.
Secondly, Newtons laws of motion deal with idealized objects which are homogenous, rigid, and free of frictional and other forces. We don’t know much about the interior of the sun, but we do know it’s surface layers are much less dense than it’s deeper layers, and that the density gradient from surface to core may not be linear. We also know the surface layers are highly mobile and fluid, and are highly magnetized. This means the sun might get jiggled around internally as it moves in it’s complicated dance around the solar system barycenter.
Thirdly, there appear to be correlations between changes in solar activity (particularly sunspot number) and the inter-related motions of the planets over the course of time. Paul D. Jose in his 1965 paper showed a coincidence between the changes in the sun’s angular momentum as it jiggled around the solar sytem’s center of mass, and the number of sunspots appearing on it’s surface.
So what’s the problem? Why is this a controversial area of research?
If the planets affect the sun, and the sun affects Earth’s climate, discovering how it works might alter the way we view climate change. Small changes in the Earth’s motion coincide with changes in climate, and Paul Vaughan has been discovering some very good correlations between these climate factors and changes in Earth’s motion caused by the other planets and the sun. Petr ‘semi’ Semerad has discovered that changes in Venus and Earth’s angular momentum coincide with the ~11 year sunspot cycles. Geoff Sharp has discovered the big outer planets move in a rhythm coinciding with drops in solar activity every ~178 years, the size of which depend on the phase of the sunspot cycle when the sudden changes in angular momentum of the sun occur.
Another problem is that just like Newton didn’t know how gravity worked (and we still don’t), we don’t yet know for sure what the mechanisms are by which the planetary motions affect the sun and individual planets, although we have a pretty good body of evidence to show they do. Several possible mechanisms have been put forward, and investigations using the available data are ongoing. These include three main areas covered by posts on this blog:
Tidal forces, similar to the tidal effects of the Moon on the Earth.
Gravitational effects on the angular momentum of different parts of the sun as it revolves in it’s peculiar orbit around the centre of mass or ‘Barycenter’ of the solar system (SSB for short).
Electromagnetic effects due to interactions between the solar and interplanetary magnetic fields and the magnetospheres of several of the planets.
Some physicists dismiss these possibilities because they believe the forces involved would be too small to have any effect on the sun. Proponents of the solar- planetary theory disagree, and believe that the possibilities must be quantified, predictions made and tests performed before the hypothesis can be falsified.
What form could these tests take?
What resources are required?
Who’s going to fund a program of investigation?
Answers on a postcard, or just add your thoughts or questions below.