>In the early 1960s, scientists realized that the surface of the Sun oscillates, expanding and contracting in regular cycles of about five minutes. [...] >"S

>In the early 1960s, scientists realized that the surface of the Sun oscillates, expanding and contracting in regular cycles of about five minutes. [...] >"Sound waves are characterized by frequency—the number of cycles that pass by a stationary point in one second. Our ears perceive frequency as pitch. The five-minute cycle of the Sun’s surface corresponds to a frequency of about 0.0033 hertz." PDS: Don't forget that anything that resonates at a particular frequency -- also has overtones and undertones of that frequency -- although those will typically be less pronounced...