The solar dynamo begins near the surface.Contrary to theories suggesting deep origins of these phenomena, helioseismology pinpoints low-latitude torsional oscillations to the outer 5 – 10% of the Sun, the near-surface shear layer. Within this zone, inwardly increasing differential rotation coupled with a poloidal magnetic field strongly implicates the magneto-rotational instability, prominent in accretion-disk theory and observed in laboratory experiments. Together, these two facts prompt the general question: whether the solar dynamo is possibly a near-surface instability. Here we report strong affirmative evidence in stark contrast to traditional models focusing on the deeper tachocline.
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The tilting angle of sunspot pairs with the leading sunspot closer to the Sun’s equator is known as Joy's law. Sunspot polarity reversal was discovered by the American astronomer, G.E. Hale, and is known as Hale's law. Sunspot groups have opposite polarity from north to south hemispheres, and the polarity reverses from cycle to cycle. If the change of solar magnetic field polarity from beginning to end is also taken into consideration, the actual period of a sunspot cycle is about 22 years.
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