Uranus & Neptune: Role in Solar Grand Minima and Solar Cycle Modulation?
Written by Geoff J. Sharp
Are Uranus & Neptune Responsible for Solar Grand Minima and Solar Cycle Modulation? Study by Geoff J. Sharp. Published in the International Journal of Astronomy and Astrophysics.
Detailed solar Angular Momentum (AM) graphs produced from the Jet Propulsion Laboratory (JPL) DE405 ephemeris display cyclic perturbations that show a very strong correlation with prior solar activity slowdowns. These same AM perturbations also occur simultaneously with known solar path changes about the Solar System Barycentre (SSB). The AM perturbations can be measured and quantified allowing analysis of past solar cycle modulations along with the 11,500 year solar proxy records (14C & 10Be). The detailed AM information also displays a recurring wave of modulation that aligns very closely with the observed sunspot record since 1650. The AM perturbation and modulation is a direct product of the outer gas giants (Uranus & Neptune).
This information gives the opportunity to predict future grand minima along with normal solar cycle strength with some confidence. A proposed mechanical link between solar activity and planetary influence via a discrepancy found in solar/planet AM along with current AM perturbations indicate solar cycle 24 & 25 will be heavily reduced in sunspot activity resembling a similar pattern to solar cycles 5 & 6 during the Dalton Minimum (1790-1830).
Solar system dynamics have been postulated as the main solar driver for many decades. Jose (1965)  was the first to associate a recurring solar system pattern of the 4 outer planets (179 years). Jose suggested this pattern correlates with the modulation of the solar cycle. New research via this study suggests that over the past 6000 years the 179 year cycle cannot be maintained and is closer to a 172 year cycle which aligns with the synodic period of Uranus & Neptune (171.44 years). Later Landscheidt (2003)  progressed the planetary influence theories further by associating quasi-cyclic negative torque readings or “zero crossings” (AM readings going below zero) that can occur near grand minima. It has been found since that the negative readings occur in the general region of most grand minima but such records are not a reliable method of predicting the timing and strength of grand minima at the solar cycle level.
Other studies detailed the orbit path of the Sun around the Solar System Barycentre (SSB) that showed a balanced trefoil pattern during times of “normal” solar cycles. Charvàtovà (2000)  shows this pattern or pathway as it moves to a disordered state during times of solar slowdown and are a direct result of the Uranus/Neptune conjunction of the era.
Theodor Landscheidt’s work has inspired both professional and citizen scientists. For example, Carl Smith (2007)  while researching Landscheidt’s work produced an AM graph using the JPL ephemeris (Figure 1). This graph for the first time clearly showed the detailed perturbations of solar AM that also coincide with past solar slowdowns along with the disordered solar path about the SSB. Carl Smith passed away in 2009 and to our knowledge was probably not aware of the hidden detail that was contained in his work, the Perturbed Angular Momentum curve holding the clue.
The perturbed curves on the solar AM graph (Figure 1) correspond with solar torque perturbations, which also alter the normal balanced solar path around the SSB. The solar velocity is also perturbed on a 172-year cycle (average) and a greater diversion between the orbital AM of the Sun and planets is observed. It is proposed through a spin orbit coupling mechanism resulting in varying solar equatorial rotation rate, the solar dynamo is reduced during these 172 year intervals.
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