The Big Wave!

At around 14:00 on March 5th 2014, SWAP, the EUV imager on PROBA2, observed a wave travelling over the solar North pole. The wave was probably generated during a strong eruption on the Northern backside of the Sun. The wave travelled at a velocity close to the estimated local sound speed and it also showed evidence that it was deflected off of other local magnetic structures. Both the velocity and deflection provide evidence for solar physicists for determining the nature of the wave, which is believed to be a fast magnetohydrodynamic (MHD) wave. A difference image and a movie of this event can be found below. 

The linked movie (and the inset grey-scale image) shows a series of images made with SWAP and a technique called "running difference". Running difference images are created by subtracting the previous image from the current one. By doing this, flows, movements and spontaneous changes in the Suns intensity are clearly seen. Enhancements or depletions in the intensity, since the previous image, are seen as white or black regions respectively. Areas which have little change are seen as grey. Running difference images are a useful tool for solar physicist, especially when looking for dynamic structures in a complicated image.

Further info can be found in the weekly STCE newsletter (3 Mar 2014 - 9 Mar 2014): http://www.stce.be/newsletter/newsletter.php