NASA’s brand new Solar Dynamics Observatory (SDO) has recorded the most stunning images of superhot plasma raining down on the solar surface. Footage recorded last week over four hours revealed one of the largest solar eruptions ever seen, in which billions of tonnes of plasma are blasted out into space. Some of the debris then falls back down to the surface, having cooled down to a relatively frosty 60,000 degrees Celsius.
While the phenomenon of coronal rain has been known for a long time, it’s always been a puzzle why it should fall back so slowly. Instruments on SDO have provided the answer by revealing detail which could never previously be observed. A layer of gas, at temperatures between one and two million degrees Celsius, is cushioning the fall, which can be seen in the attached video.
A much more detailed write-up can be found at http://science.nasa.gov/science-news/science-at-nasa/2010/27apr10_plasmarain/.