Last night at 23.16 UTC we had our sec­ond X-class solar flare this year. This is very rare. Solar flares are clas­si­fied as A, B, C, M or X accord­ing to the peak flux. X-class is the biggest. The first big flare this year was on Valen­tines Day ♥ . Other large solar flares also occurred on April 2, 2001, Novem­ber 4, 2003, Sep­tem­ber 7, 2005. Here’s a list of the most pow­er­ful solar flares. — Arthur