Sunday, December 21, 2014

Active Sun Unleashes Significant Solar Flares

Image of the Sun on Dec. 20, 2014. Credit: NASA/Solar Dynamics Observatory

The sun unleashed a massive solar flare on Dec. 19 (Dec. 20 UTC) that erupted from a sunspot region classified as Active Region 2242. Earlier in the week, another active sunspot region called AR 2241 fired off two intense M-class flares, on Dec. 16 registering as an M8.7-class, and the other on Dec. 18, an M6.9 solar flare. The latest solar flare was registered as an X1.8-class event, one of the most powerful types of flares possible. A pulse of X-rays and UV radiation from the flare reached Earth minutes after the explosion. This "solar EMP" ionized our planet's upper atmosphere and blacked out HF radio communications over Australia and the South Pacific. Below 10 MHz, transmissions were strongly attenuated for more than two hours.

The explosion also hurled a coronal mass ejection (CME) into space. Although the instigating flare was Earth-directed, it appears that the CME is not. The bulk of the cloud will sail far south of he sun-Earth line, missing our planet.

Radio blackouts reaching the R3 levels were observed over the past 24 hours. The largest was at Dec. 20 at 00:30 UTC.

The region AR 2241 remains large and complex. More minor to moderate radio blackouts are expected, with an ongoing chance for another strong event.

Sunspots on the sun are areas of complex and intense magnetic fields, which can produce eruptions on the sun such as solar flares. Each is labeled by NOAA with a number. Image Credit: NASA/SDO/HMI/TheSunToday
Sunspots on the sun are areas of complex and intense magnetic fields, which can produce eruptions on the sun such as solar flares. Each is labeled by NOAA with a number. Image Credit: NASA/SDO/HMI/TheSunToday

Forecasters are still awaiting the arrival of the 17 and 18 Dec CMEs. Both are expected to arrive at Earth sometime on 21 Dec, possibly producing moderate geomagnetic storming.

There could be an increased chance to see the aurora across southern Canada and possibly along the northern border of the U.S. - given a cloud free night. 

Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel.

M-class flares are a tenth the size of the most intense flares, the X-class flares. The number provides more information about its strength. An M2 is twice as intense as an M1, an M3 is three times as intense, etc. 

Credit: NASAspaceweather.comNOAA

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