Tidal forces of Venus, Earth and Jupiter have a significant impact on the solar magnetic field, thereby controlling its 11-year activity cycle, as well as the behavior of plasma in the transition layer of our sun.

One of the biggest questions of solar physics is its regular 11-year cycle. It is characterized by a rather rapid increase in the number of sunspots, as well as other manifestations of activity and a subsequent, slower decline. During the cycle, other periodic changes are observed, for example, a gradual displacement of the zone of formation of sunspots towards the equator.

There is a surprisingly high level of consistency: we see complete parallelism with the planets for 90 cycles. Everything points to a synchronized process.

-Frank Stephanie, lead author of the study from the Institute of Hydrodynamics at the Research Center for them. Helmholtz Dresden-Rossendorf (Germany)

In principle, the magnetic activity of stars like ours is often subject to cyclic oscillations, and yet previous models could not accurately explain the very strict cycle of the sun.

In order to solve this multi-year question, a team of physicists compared historical observations of solar activity over the past thousand years with the planets, statistically proving that their tidal forces act as external clocks and are a decisive factor behind the steady rhythm of the Sun.

As is the case with the gravitational attraction of the Moon, causing tides on Earth, the planets are able to influence the hot plasma on the surface of the Sun. At the same time, tidal forces reach a maximum with exact alignment of Venus, Earth and Jupiter, which occurs every 11.07 years.

But the effect is too weak to substantially perturb the flow in the depths of the Sun, so this coincidence has long been neglected. However, researchers have found evidence of a potential indirect mechanism that can influence the solar magnetic field through tidal forces: fluctuations in Taylor instability, the physical effect that occurs when a strong magnetic field passes through a conductive layer or plasma. Based on this concept, scientists have developed a model that reveals a realistic scenario.
Small impact with serious consequences.

In the hot plasma of the Sun, Taylor’s instability perturbs the flow and magnetic field, while it itself reacts very sensitively to tiny forces. A small impulse is enough for the disturbances to begin to oscillate between the right and left screw. The impetus required to launch this process can be created by planetary tidal forces every eleven years, which ultimately also sets the rhythm at which the magnetic field changes the polarity of the Sun.

When I first read about the ideas linking the solar dynamo with the planets, I was very skeptical. But when we discovered in our computer simulations Taylor’s controlled instability, experiencing helicity fluctuations, I asked myself: what happens if a small disturbance like a tide influences the plasma? The result was phenomenal. The oscillations turned out to be really synchronized with the moment of external disturbance.

-Frank Stephanie

Solar dinamo and the planets

In the standard scenario, the rotation of the sun and the complex movement of the solar plasma create a cyclically varying magnetic field. Two effects interact here:

  • omega effect: the plasma rotates at the solar equator faster than at the poles, this leads to the fact that the magnetic field lines trapped in it stretch around the sun and convert the magnetic field into an alignment almost parallel to the solar equator;
  • the alpha effect describes a mechanism that twists the lines of a magnetic field, causing it to return in a north-south direction.

However, what exactly causes the alpha effect is the subject of controversy. The model developed by Frank Stephanie and his colleagues shows that Taylor instability is partly responsible for this. Physicists consider the most likely scenario in which the classical solar dynamo is combined with the modulations generated by the planets.

In this case, the Sun becomes a completely ordinary old star, whose dynamo cycle is synchronized with the tides. The great thing about our new model is that now we can easily explain the effects that were previously difficult to model, such as the “false” spirals observed on sunspots, or the well-known double peak on the Sun activity curve.

-Frank Stephanie

How does the planets affect our sun
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