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The Question

(Submitted January 27, 1998)

I am probably way out of my league here, as I am barely qualified to call myself an amateur astronomer. But I was contemplating the Sunspot cycle and was wondering what the odds were that it could be a product of Jupiter's orbit? Would appreciate any comments you might have on this.

The Answer

This is a really excellent question. The sunspot cycle is caused by the flip of the solar magnetic field approximately every 11 years (close to the 11.86 year period of Jupiter's orbit). The exact reasons why the Sun's field flips are not known, but it has it's basis in irregularities in the plasma dynamo at the core of the Sun that generates the magnetic field. It seems plausible that tidal effects from Jupiter are one of the perturbations that cause these irregularities, but not the only one. The earth's magnetic field flips as well, although not as regularly as the Sun's, and lunar tidal effects probably contribute. For more information on the solar cycle, you can look at:

Eric Christian
for Ask an Astrophysicist

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