PROPAGATION
A new discovery was made by observations of the Sun using a decade of data from NASA’s Solar Dynamics Observatory (SDO). As reported on July 20th in the journal Astronomy & Astrophysics <https://tinyurl.com/3cnc8mtu>, the observations revealed huge churning and writhing waves on the surface of the Sun. We’ve known that waves move up and down with periods — the time between each wave peak — of only five minutes. It was 60 years ago that scientists first discovered these waves, but now, scientists have discovered much more slowly oscillating waves in the Sun’s surface. These newly-discovered waves have periods comparable to the Sun’s 27-day rotation.
Over a period of approximately 27 days, the Sun makes one rotation, and we watch sunspot regions traverse the visible Sun’s surface with these rotations. But the last decade of SDO’s observations have revealed these slow-moving waves move across the solar disc, too.
The observations revealed huge swirling waves which extend 125,000 miles below the surface of the Sun. Computer models showed the waves are caused by the Sun’s rotation, which is faster at the equator than the poles.
The waves are. The solar dynamo is thought to be responsible for the features and eruptions on the Sun’s surface that vary in intensity over the approximate 11-year cycle of solar activity. Right now, we are in the 25 such solar cycle since they have been recorded by solar scientists.
