Solar sunspot group, active region (AR) 11109, is rotating out of view over the western limb of the sun.
As it was moving out of the view of the earth and SDO it produced a C-class (C2.3) solar flare at 16:38 UT, October 4th.
A full sun image observed by SDO.
- The greenish color is 171 Angstrom extreme ultraviolet light.
- The yellow and blue colors are the positive and negative polarity magnetic field respectively.
This video first shows the flare observed by the Solar Dynamics Observatory (SDO) in the 171 Angstrom wavelength of extreme ultraviolet light.
The small but bright flare causes up and down lines on the CCD (similar the kind used in digital cameras). The same thing happens on many digital cameras when taking a picture of a very strong light source such as the sun.
Next, the video shows the flare observed by in SDO in the 304 Angstrom wavelength. This time the flare causes a cross shaped pattern of parallel lines. This is caused by diffraction of the light by a coating on the 304 Angstrom filter.
The trace on the graph at the top of the two movies shows the x-rays measured by the GOES satellite at the same time as the observations by SDO. The size classification for solar flares (e.g. C-class) is determined from the strength of the X-rays measured by GOES. This classification system is much like the Richter scale for earthquakes. (credit for movie and images: Sam Freeland and SDO)