User highlight: oscillating coronal loop
As the movie progresses, you see a small eruption take place. As the eruption starts, you can clearly see the southern base of the loop displace. The loop appears to be released in some way, which shakes the whole loop along its entire length. This event is a great example of a transverse coronal loop oscillation. These were first observed by the Transition Region and Coronal Explorer (TRACE) in 1998. Since these initial observations, many more examples have been observed, by both TRACE and AIA. The mechanism of the excitation of these waves remains hidden, but it can be connected with a blast wave generated in a flare epicentre. For scale, the Earth is roughly the same size as the Helioviewer logo in the bottom right hand corner of the movie.
although it is much more difficult to see in the AIA 193 Angstrom channel compared to the AIA 171 Angstrom channedl(the dark wavy material you see are motions in a prominence, not the same as the coronal loop oscillation).
Observations of coronal loop oscillations, coupled with a theoretical understanding of how these oscillations behave in the coronal plasma has lead to a new field of study called coronal seismology. Coronal seismology is analogous to seismology on Earth. Seismology is the study of earthquakes and the propagation of waves arising from earthquakes, and can be used to infer properties of the structure of the Earth. Similarly, coronal seismology is used to measure properties of the Sun’s coronal plasma. Using coronal seismology, we can derive the density and magnetic field of the coronal plasma, measurements that are difficult make in other ways.