For all we’re learning about the distant cosmos, there’s still much we don’t understand about things much closer to us, like the Sun. It’s difficult to investigate something as big and hot as the Sun up close, so astronomers have to use other means, like tapping into the hidden sound waves from deep inside the star. When astronomers compiled 40 years’ worth of helioseismic data—information on the waves propagating inside the Sun—they found a previously unknown pattern of solar magnetic activity bunching up into a shallow layer just below the surface. In a new paper published today in Monthly Notices of the Royal Astronomical Society, researchers describe how this internal “biorhythm” points to changes in solar activity that weren’t observable via traditional methods. “We discovered that the relationship between internal solar oscillations and surface activity has evolved over the past few cycles,” Sarbani Basu, a study co-author and an astronomer at Yale University, said in a statement. “This trend cannot be explained simply by weaker magnetic fields.”
From down under According to the paper, the two previous solar cycles deviated slightly from previous ones. Cycle 24 (2008 to 2019) was significantly weaker. Meanwhile, solar cycle 25, which we’re currently in, was initially predicted to be “below average” by experts but ended up overshooting expectations in terms of the number of sunspots and radio activity.
