What is the Planetary Theory about? Why all the Fuss?

Over the last five years there’s been a revival of an old hypothesis which suggests that the motion of the planets around the Sun modulates its output, and that variation in the Sun’s output affects the Earth’s weather and in the longer term, shifts in regional and global climate. This revival has been most visible here in the blogosphere, where ideas can be kicked around with less professional reputational risk, and a faster exchange and development of concepts and narratives can take place. There has also been a steady trickle of papers published in the scientific literature relevant to the theory, and these have been championed and denigrated by bloggers on both sides of the issue.

Naturally, in the overheated atmosphere of the climate debate, the second part of the idea is especially controversial, with the Intergovernmental Panel on Climate Change telling us that human emitted ‘greenhouse gases’ are the primary driver of global warming since the middle of the last century. They also say the Sun’s variation has very little effect on climate change. An IPCC author recently took exception to our special edition on the theory and got the journal we published it in axed. The first part of the idea is controversial too, as the received wisdom from most mainstream solar physicists is that the planets are too small and too far from the Sun for their motion to affect it. They are sure that the Sun runs an internal ‘dynamo’ (Babcock & Leighton) and ‘chronometer’ (Dicke) which accounts for the observations of its cyclic variations that have been made over the centuries.

It’s best to break it down and separate these two issues, so we can look at the merits of the individual parts of the theory and discuss them. In this post I’ll just deal with the first part of the theory, so it doesn’t get too long. Even this first part is a big subject so I’ll briefly gloss it in this post, with links to previous posts and other material embedded for those who find the subject interesting to refer to.

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 its radiation, keeping them in their orbits with its gravity, warding off a lot of the galactic cosmic rays from entering with its solar wind etc), the planets also have an effect on each other, and on the sun, causing its 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 the 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 its effect 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, point-like  and free of frictional and other forces. We don’t know much about the interior of the sun, but we do know its surface layers are much less dense than its 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 and that vast amounts of energy are pouring through them from the interior and out into interplanetary space. It is surrounded by the heliomagnetic field it generates, and this has magnetic fields ‘frozen in’ to the plasma it ejects into space. This means the sun might get jiggled around internally as it moves in its 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 its surface. This correlation has recently been investigated by the world’s foremost experts on using proxy records of radio-nucleides such as the Carbon 14 and Beryllium 10 isotopes. They have found that the Fourier analysis of the time series they have produced shows periodicities which match periods occurring in the interactions of the planets as they revolve about the Sun. My co-blogger Tim Channon has created a model of these periods which generates a curve which matches the data quite well, considering the difficulties and uncertainties involved in the analysis of core samples used in building the isotope time series. Here’s a plot covering 9000 years of solar activity variation as reconstructed from the Beryllium 10 and Carbon 14 proxies.

 

Steinhilber, Beer and Frohlich 2009 10Be proxy reconstruction of solar activity vs model generated from planetary periods.

Another contributor at this website, R.J Salvador, has built a model using planetary periods which replicates the Sun’s output over the period of the sunspot record from 1749 which achieves a correlation of over 90%

R.J Salvador’s solar-planetary model (white line) vs sunspot number

In my own research, I found that when the speed of the solar wind is taken into account, and the alignment of the planets is considered along the lines of energy emitted from the Sun called the Parker Spiral, the simple planetary alignment index created by NASA scientist Ching Cheh Hung can emulate not only the timings of the solar cycles well, but their shape too in some cases.

Plot generated using a modified version of Roy Martin’s tidal model

This should be enough to whet the appetite of those who haven’t seen this stuff before, and are interested to find out more. In the next post on the Planetary Theory, I’ll go into some more detail on the various mechanisms which have been proposed to explain the correlations which clearly exist. That’ll also give me the opportunity to introduce some of the other researchers involved in developing the Planetary Theory.