The pulse of the Sun's dynamo
Deep inside the Sun, around the level of a suspected dynamo (white line), speeds of gas circulation change markedly over 6 months, during pulsations that take 16 months. Relatively fast motions are shown in white, and slower motions in black.
Meanwhile near the surface (seen plainly on the left of the cutaways) bands of faster and slower gas move towards the equator. The GONG network of ground observatories and the SOHO spacecraft revealed the deep pulses by monitoring sound waves passing through the Sun. CREDIT: GONG (NSO/NSF) and SOHO/MDI (ESA & NASA)