Did you know there are 'earthquakes' on the Sun? They are called sunquakes and their study can lead to a better understanding of the conditions inside the Sun. Dr. Sarah Matthew, from the University College London (UK), writes about them.
A sunquake is a short-lived seismic disturbance in the interior of the Sun seen with some solar flares and coronal mass ejections (CME) as propagating ripples on the surface. Like earthquakes, sunquakes have the potential to help us understand conditions inside the Sun, but they are also a puzzle from the perspective that they aren’t seen with every flare/CME, and even when they are seen, they are only in very specific locations, which means there must be some special set of conditions necessary for them to happen.
Unlike most earthquakes, the trigger for sunquakes seems to come from above, like fracking induced earthquakes here on Earth. But while we know that fracking involves high pressure jets of liquid, we don’t know what the equivalent agent is on the Sun, or importantly, how the energy gets channelled to specific locations. We do know that energy gets released from the magnetic field high in the solar corona during a flare or a coronal mass ejection, so one possibility is that the magnetic field creates a kind of lens when we see a sunquake, that focuses the energy in a small area.
At the moment we can only really measure the magnetic field in the photosphere, but we know that there are big changes higher up in the atmosphere that mean we need to measure the field at several heights, especially in the chromosphere. The European Solar Telescope will be able to simultaneously measure the magnetic field in the photosphere and chromosphere at multiple heights which will enable us to figure out if this is really happening and perhaps solve the mystery of susnquakes.
More info in the related paper: Kosovichev & Zharkova, Nature, Volume 393, Issue 6683, pp. 317-318 (1998). Image and video credits: http://soi.stanford.edu/press/agu05-98/