The sun emitted a mid-level solar flare on Oct. 23, 2013 that peaked around 8:30 PM ET. A solar flare is essentially a burst of radiation. Thankfully, Earth's atmosphere protects us from harmful radiation. If a solar flare is intense enough it can disturb the atmosphere in the layer where GPS and communications signals travel. The radio signals can be disrupted as long as the flare is ongoing, anywhere from minutes to hours.
This flare is classified as an M9.4 flare, on a scale from M1 to M9.9. This rating puts it at the very top of the scale for M class flares, which are the weakest flares that can cause some space weather effects near Earth. In the past, they have caused brief radio blackouts at the poles. The next highest level is X-class, which denotes the most intense flares.
Since the sun is near a solar maximum there has been an increase in the number of solar flares. Scientist have been tracking solar cycles since they were discovered in 1843, and it is normal for there to be many flares a day during the sun's peak activity.
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