On Oct 22, 2012, the sun released a massive solar flare that peaked at 2:51 p.m. EDT. It originated from the recently named AR 1598 sunspot, which has already emitted several weaker flares. This flare was directed away from the Earth, but as AR 1598 turns towards us in the next few days it may send one our way. Looking farther in the future, the frequency of such flares is expected to increase in the next two years as the sun’s 11-year cycle ramps up to its peak in 2013. This cycle in flares signal a deeper cycle: the switching of the sun’s magnetic poles, which reverse their polarity every 11 years.
Video of the Oct. 22, 2012, solar flare as captured by NASA's Solar Dynamics Observatory (SDO) in the 131 and 304 Angstrom wavelengths. (Credit: NASA/SDO/Goddard)
Before you build a bunker to hide from the impending increase in solar flares, though, keep in mind that any harmful radiation cannot pass through the Earth’s atmosphere to affect people on the ground. At most, they are able to affect satellites, radio and other electronic devices. The Oct. 22 flare knocked out high-frequency radio for a short period.
Solar flares are an intense emission of electromagnetic radiation at all frequencies — ranging from radio waves to visible light to X and gamma rays. This was an especially large, X1.8-class flare, and it is the fifteenth X-class flare in this solar cycle. X is the largest class; as for the numbers, an X2 would be twice as intense as an X1. The previous flares from AR1598 were given an M classification, which is one step down from X, and corresponds to an order of magnitude less electromagnetic flux.
Occasionally, when very large solar flares are associated with a coronal mass ejection — essentially a stream of charged particles — they can even knock out electrical power. The most recent Oct. 22 solar flare did not have a coronal mass ejection; however, the two are often associated with each other.
Coronal mass ejections, though they are known to interfere with GPS and electrical power, have their upsides too. The aurora borealis is caused by the interaction of those charged particles with the Earth’s magnetic field, creating brilliant displays of light and color near the poles.