The sun is about to enter a period of quiet, known as a solar minimum. This cycle happens every 11 years and is characterized of decreased activity—when sunspots fade away and produce fewer solar flares. With this latest period of inactivity approaching, scientists have been monitoring the sun to better understand some of the unusual activity observed over recent years.

In a study published in May the Monthly Notices of the Royal Astronomical Society, a team of scientists from the U.S., U.K. and Denmark analyzed 31 years’ worth of data from the Birmingham Solar Oscillations Network (BiSON)—a group of six ground-based telescopes that provide constant monitoring of the sun’s oscillations. In the study, Yvonne Elsworth and colleagues studied the sound waves from the sun over the last three solar minimums to see how they have changed during different periods of activity. Elsworth will present the findings at the National Astronomy Meeting at the University of Hull, U.K., on Tuesday.

“The sun is very much like a musical instrument except that its typical notes are at a very low frequency—some 100,000 times lower than middle C,” she said in […]