In Science and Space: Sunspots have been used to gauge the sun’s cycle for 400 years, but a recently proposed “circle of fifths” system may be able to foretell hazardous and violent solar outbursts years in advance.
The new framework was proposed by Robert Leamon, a scientist with the Partnership for Heliophysics and Space Environment Research (PHaSER). It is based on research showing that significant and occasionally dramatic changes in the solar cycle occur with a rhythm every fifth of a cycle.
According to recent research, a “solar clock” based on the magnetic field of the sun may be a more accurate way to forecast hazardous solar flares that pose a threat to Earth’s communications systems years in advance.
Leamon and his team refer to the periodicity as a “circle of fifths,” and they believe that even while solar cycles can vary by months or even years, they nevertheless follow a distinct and foreseeable pattern of events.
With each new solar cycle, the Sun’s magnetic field turns from one pole to the other, but there are overlaps between cycles in which the change is not complete. Terminators represent points in the cycle where the alignment of the previous cycle has completely disappeared from the surface of the Sun. This point is accompanied by a sudden and rapid increase in solar activity, and Leamon suggests that solar cycle landmarks are more distinct and consistent from terminator to terminator than sunspot activity. This could make the use of Terminator a better way to measure the solar cycle.
Leamon and his colleagues used data collected by the Dominion Radio Astrophysical Observatory in Penticton, Canada, and his Wilcox Solar Observatory at Stanford University to identify solar cycle patterns. “How many different sun’s can we see? And they’re all the same he turns out to overlap in sets of 5 degrees,” Leamon says. They found that changes occur exactly every fifth cycle. Two-fifths of the cycle, a dark region known as the polar coronal hole formed at the Sun’s poles. At 3/5, the Sun emitted the last X-class flare of this cycle. This is a powerful and potentially dangerous kind of solar flare.
It is less consistent, reaching a sunspot minimum in the Sun’s photosphere four fifths of the cycle. Then the final event of the cycle, the Sun, passes through another Terminator.