Past and future of deep time Solar Cycles

Published in the WANSAC (Western & Northern Suburbs Amateur Radio Club) monthly club magazine  Vol 40 Issue August 2009

http://www.wansarc.org.au/

THE RESTLESS SUN -  ORDER AND CHAOS by Peter Miles

Past and future of deep time Solar Cycles

The somewhat orderly solar cycles that have been observed for a little over three hundred years have ebbed and flowed, resulting in intense solar maximums (peaks of sunspot and solar activity) and sometimes minimal activity. When there have been successive periods of low-intensity solar cycles, they appear to have a connection with general climatic conditions on Earth. The Maunder Minimum, which occurred from about 1650 to 1715, is a notable example, characterized by very few reports of sunspots and coinciding with the coldest part of the period known as the Little Ice Age.

The absence or high activity of sunspots does not seem to have a significant observable effect on total solar output, which has led to the struggle to establish a credible connection between sunspot activity and the Earth's climate. However, historical records of climate and sunspot activity indicate a correlation, suggesting that sunspot activity may be a contributing factor, as seen during the relatively recent Dalton Minimum. The Dalton Minimum, a period of low solar activity lasting from about 1790 to 1820, also coincided with below-average global temperatures.

The cooler temperatures during the Dalton Minimum were exacerbated by the 1815 eruption of Mount Tambora on the island of Sumbawa, now part of Indonesia. This volcanic eruption made the winter of 1816 one of the most miserable and deadly on record. While the eruption worsened the situation, the cold spell had already begun around 1810.

Researchers have determined solar activity for the past 11,000 years using the carbon-14 proxy record. The Earth is constantly exposed to cosmic rays from deep space, which produce carbon-14 in the atmosphere. Trees, even in their dead state, retain a record of the levels of carbon-14 produced over an extended period. During periods of high sunspot activity, charged particles from the Sun repel cosmic rays, resulting in lower carbon-14 levels recorded in tree rings. By examining carbon-14 levels, scientists have estimated sunspot numbers as far back as 11,400 years.

This comprehensive record of solar activity reveals a striking correlation between low solar activity and well-documented periods of cool climate throughout history. These seemingly random periods of low sunspot activity may exhibit more order and predictability than initially perceived.

In an interesting 1999 paper by I. Charvátová on Celestial Barycentrics (the orbital mechanics of the solar system), it is speculated that much longer-duration cycles impact the behavior of the Sun and, by extension, Earth's climatic conditions. It is not widely appreciated that the planets of the solar system do not actually orbit around the Sun; instead, including the Sun itself, they orbit around the center of mass of the entire solar system. While the Sun, representing 99.8% of the total solar system's mass, orbits a point very close to the center, it can deviate from it by more than the diameter of the Sun. The mechanics of objects orbiting the central point of mass in a celestial system become more apparent when observing binary star systems. In a two-star system with identical masses, both stars will orbit around a point halfway between them.

Our Sun is influenced by the distribution of the total solar system's mass, primarily by the positions of the four largest planets in order of mass: Jupiter, Saturn, Uranus, and Neptune. The plot below illustrates the Sun's position in relation to the center point of the solar system over a fifty-year period from 1945 to 1995, clearly demonstrating the dynamics of this gravitational interplay among the system's heavyweights (see Fig. 1).

In fact, astronomers are able to determine the presence of planets, their size, and their orbits around distant stars by observing the wobble of those stars. This technique, known as the radial velocity method or Doppler spectroscopy, has been instrumental in the discovery of all the known exoplanets (planets outside of our solar system) to date.

Fig. 1: The sun's diameter is marked by a thick circle. The position of the centre of mass relative to the sun's center is indicated by a cross, and the respective years are indicated by small circles.

 
The orbit of our Sun around the central and moving centre of mass of the solar system generally forms a well-ordered pattern referred to as a Trefoil. See below for the Trefoil pattern.

Fig. 2: Trefoil pattern sometimes referred to as the trefoil knot.

The Trefoil pattern, or something resembling it, is the norm and appears to be associated with long periods of relatively consistent solar cycles. However, occasionally this pattern is disrupted, and a period of disordered motion affects the Sun. This abnormal disordered period appears to be associated with less sunspot activity and generally lower temperatures here on Earth.

The study by the author proposes that the four most influential planets orbiting our Sun produce a number of repeating cycles: a 2402-year cycle, several 178-year periods within the 2402 years, and a 370-year period also within the 2402-year cycle. The study also reveals the order and chaos within the motions of the Sun around the centre of mass during these periods.

The diagram below shows the Sun's path around the centre of mass of the solar system for defined periods of time, starting from the year 1192 to the year 2134. The six upper plots show the Sun's path in the orderly Trefoil-type pattern, while the lower five plots show the disordered path and the corresponding grand minima that resulted in temperature plunges on Earth.

Fig. 3: Diagram illustrating the Sun's path around the centre of mass of the solar system for defined periods of time, spanning from the year 1192 to the year 2134. It is noteworthy that we are currently entering (since 1985 and continuing until 2040) one of these periods characterized by "disordered" motion. What is particularly intriguing is that the last four instances of such "disordered" periods coincided with the climate minimums known as the "Wolf," "Sporer," "Maunder," and "Dalton" minimums.

The table below provides a clear depiction of the relative rarity of grand minimums; however, it also illustrates their potential to endure for a considerable duration.

What’s this have to do with radio?

The solar cycles have a clear impact on radio propagation, especially on the HF and low VHF bands. However, applying these long-duration cycles practically to ham radio operations, which often span several generations, can be challenging. Nonetheless, they remain a subject of interest and speculation regarding the upcoming cycles and the workings of this fascinating natural phenomenon. Of particular interest is the new cycle 24 and its potential development within the context of the proposed period of disordered motion described in the author's paper. It offers an opportunity to gain a deeper understanding of not only the solar cycles but also the subtle effects they have on Earth's climatic conditions.

If a grand minimum were to occur, the depressed HF conditions experienced since 2008 could become the norm for the next few generations. While this may be disappointing for those anticipating a significant solar maximum, there are potentially more significant concerns beyond missing out on fantastic F2 openings to Hawaii on the six-meter band. Historical evidence suggests that a grand minimum could disrupt food production, contribute to famines, and pose direct threats to individuals living in extreme northern and southern latitudes.

Although Charvâtova's paper may not currently hold a prominent position in the ongoing scientific discussions, its validity and significance will be determined by the passage of time and further observations. It is through continuous testing, observation, and analysis that we can refine our understanding of the intricate relationship between Earth and its inhabitants with the greater universe.

For more information on long term solar cycles. See:

http://www.ann-geophys.net/18/399/2000/angeo-18-399-2000.pdf

Author: I. Charvâtova

Geophysical Institute AS CR, Bočnĭ II, 141 31 Praha 4, Czech Republic

Received: 30 September 1999 / Revised: 14 January 2000 / Accepted: 17 January 2000

For more information on centre of mass dynamics. See:

http://astro.unl.edu/naap/esp/centerofmass.html

For more information on Extrasolar planets. See:

http://en.wikipedia.org/wiki/Extrasolar_planet

For more information on the effects of grand minimums on climate. See:

http://en.wikipedia.org/wiki/Little_Ice_Age

Also see earlier article ‘The Restless Sun - Past and Future of the Solar Cycle’

(Published in the WANSAC magazine  Vol 38 Issue September and October 200)

http://vk6ysf.com/solarcycles1.htm

Cheers, Happy DXing and keep warm!

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