What Kind of Sunspot is That?

March 5, 2019: Today, a tiny sunspot is struggling to form in the sun’s northern hemisphere. It is so small, it has not yet been numbered, and it may fade away before the day is done, leaving the sunspot number technically zero. Even if it vanishes, though, this funny little sunspot is worth mentioning because of its tilted magnetic field:

This is a magnetogram (magnetic map) of the sun obtained on March 5th by NASA’s Solar Dynamics Observatory. The sunspot is inset. Note how its magnetic field is almost orthogonal to other patches of magnetism elsewhere on the solar disk.

Sunspots are islands of magnetism floating on the surface of the sun. Like all magnets, they have two poles, plus (+) and minus (-). Usually these poles are aligned almost parallel to the sun’s equator. Today’s sunspot is almost perpendicular.

Could this be a sunspot from the next solar cycle? Right now, Solar Cycle 24 is decaying into a deep Solar Minimum. Solar Cycle 25 is still in the offing. According to Hale’s Law, sunspot magnetic fields reverse polarity between solar cycles. If this sunspot continues to grow–and if its magnetic axis tilts a bit to the right–Hale’s Law would tag it as a member of Solar Cycle 25.

Postscript: The sunspot did continue to grow, and its magnetic field remained ambiguous. Based on its relatively low latitude, we believe it is probably a member of old Solar Cycle 24.

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