Hi,

On the Sun there are areas with really complicated loops of magnetic fields. Sometimes these loops twist around or cross each other and then 'reconnect' - basically one side of one loop breaks and joins a side of the other loop to make two different loops (one of which is often detached and shoots away from the Sun). When this reconnection happens it can accelerate particles, some of which travel down the legs of the new loop towards the Sun and hit the denser part of the solar atmosphere. When this happens they produce a flash of x-rays (as well as emission at other wavelengths) which is the solar flare.

If the reconnection creates a large loop that moves explosively away from the Sun, we call that a coronal mass ejection.

-Christina

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