The active region on the Sun that created all the hubbub and aurorae earlier this week put out one last shot before that area of the Sun turns away from Earth’s view. And that shot was a biggie. At 18:37 UT (1:37 pm EST) today (January 27, 2012) sunspot 1402 unleashed an X-class flare, the largest and most powerful category of flares. This flare was measured as an X2, which is at the low end of the highest powered flares, but still, this is the most powerful flare so far this year. It was not directed at Earth, but scientists from the Solar Dynamics Observatory say the energetic protons accelerated by the blast are now surrounding our planet and a S1-class radiation storm is in progress. S1-class is the lowest of 5 (S1 to S5) and has no biological impact, no satellite operations are impacted but some minor impact on HF radio could be experienced.
With all the activity from the Sun, you might need a refresher course in solar flares. Here’s a guide from SDO, and what all the different classifications are:
Source: Universe Today