© Charles Chandler

 

A rainy day on the Sun! This TRACE movie, taken on 30 June 2000, from 15UT to 16:30UT in the 195Å passband (1.5 million degrees) shows coronal loops cooling rapidly. The loops are initially at a temperature of around 3 million degrees, when they are not visible to TRACE. As they cool, the become bright at the TRACE wavelength; as their temperature drops below 1 million degrees, they rapidly fade again. But the material continues to cool: the dark blobs sliding down the loops (known as coronal rain) are so cool (probably well below 100,000 degrees) that enough non-ionized hydrogen exists to cause the EUV light to be extinguished. So very close to another, the temperatures in the corona range over a factor of close to one hundred! Look at the 1.8MB QuickTime movie to see the cool material slide down the magnetic field, pulled down by the strong solar gravity.

http://trace.lmsal.com/POD/TRACEpodarchive2.html

 

Equinox flare   On 21 March 2001, an M1.8 flare occurred in Active Region 9373, starting at 02:28UT, and peaking (in X-rays) around 02:37UT. The flare was associated with a spray of cool material (probably the result of the eruption of a small filament): material is thrown up to a height of approximately 50,000 km, and mostly slides back down again. More interestingly, however, is that the coronal loops seen over the solar edge are somehow driven to oscillate (see this QuickTime; JPEG compressed; 4.7MB) movie). The oscillations damp rapidly: only three to four back-and-forth swings are seen, with a period that appears to lie around 10 minutes. This phenomenon is very rare; it is interesting because these coronal quakes tell us things about the properties of the coronal magnetic field that are very hard to derive by other means. http://trace.lmsal.com/POD/TRACEpodarchive7.html