Powerful X1.3 Solar Flare Causes Radio Blackout

The Sun unfurled a powerful X-class solar flare early Friday, triggering a brief radio blackout on the daylight side of the Earth.

Lasting nearly two hours, the X1.3-class flare came from departing sunspot AR2016, reaching its peak intensity at 00:27 UT, or 8:27 p.m. EDT on April 24.

Solar flares are powerful bursts of radiation. Humans on Earth are protected from solar flares by the atmosphere, but when strong enough, solar flares can disrupt the layer of the atmosphere where GPS and communications signals travel, NASA said in a statement released Friday in response to the flare.

Solar flares can also trigger coronal mass ejections, or CMEs, which are massive bursts of solar wind and magnetic fields. Friday's solar flare did trigger a CME, but it is not directed towards Earth, leaving possibilities of a geomagnetic storm - leading to intensified aurora borealis - low.

There are several classes of solar flares, but M-class and X-class are most noteworthy because they can cause geomagnetic storms on Earth. M-class flares are the weakest type of solar flare that can cause some space weather effects near Earth, while X-class flares are the most powerful class of solar flare.

The numbers following a solar flare's letter class provide more information about the flare's strength. An X2 flare, for instance, is twice as strong as an X1.

SpaceWeather.com has uploaded some videos of Friday solar flare which reveal the intensity of the event.

The largest solar flare released this year was an X4.9 which occurred on Feb. 25, surpassing all X-class flares in recent memory. The largest solar flare of 2013 was rated X3.3. 

The strongest solar flare in this 11-year solar cycle, which started in February 2011, was an X6.9 that occurred in August 2011.