Our Eyes on the Sun

SDO Catches a Big One

The February 13, 2011 M6.6 solar flare. Courtesy NASA/SDO

If you’re cold, this picture should warm you up!  It shows a solar flare that erupted yesterday (February 13 at 17:38 UT).  It’s the largest such event so far in this current solar cycle (based on x-ray irradiance) and the strongest one so far in 2011.  The Solar Dynamics Observatory (SDO) caught the scene and flashed it up late Sunday. This amazing solar observatory was launched a year ago and has been sending back a steady stream of amazing images and data, all chronicling the activities of our nearest star.

Solar flares, coronal mass ejections and other actions are part and parcel of the Sun’s seethingly active surface and atmosphere, and these outbursts sometimes affect Earth and our technology. Hence, it’s important to study the Sun, if for no other reason to protect ourselves AND understand how the Sun affects Earth and its climate.  The Sun is currently ramping up in its 11-year cycle of activity, with the maximum period of activity (called “Solar Max”) to occur in 2013. This is a well-known cycle — and scientists are still working to understand all the nuances of activity that the Sun shows throughout the 11 years.

The solar flare you see in this image is a large explosion that occurred in the Sun’s atmosphere. It releases huge amounts of energy, particularly in x-ray and ultraviolet wavelengths. What powers a solar flare?  There is a huge amount of magnetic energy stored up in the corona.  Magnetic energy is stored up as magnetic fields twist and interact with each other. The process involvesd something called “magnetic reconnection”.

The Sun’s surface and atmosphere are threaded through with many lines of magnetic force. Those lines twist and turn, and rearrange over very quick timescales. Imagine a million tiny little rubber bands twisting and and twisting, and as they do, energy is built up. At some point, the tension is too much, and when two magnetic fields that have opposite “charges” or “polarity” are brought together, the fields snap.  That “snap” is accompanied by a huge release of energy. This magnetic reconnection is a complex situation and it happens very rapidly. X-rays and UV radiation is emitted, and that’s what SDO detected in the image you see above.

If the flare is big enough, the activity is also accompanied by a release of charged particles (plasma) and the event forms a coronal mass ejection.

The most obvious effect that this flare (and any coronal mass ejections) will have on Earth will show up as increased auroral displays at the polar regions.  Orbiting satellites and the International Space Station will detect radiation from the flare, as well.  As flares go, this one was pretty powerful (although not as powerful as an X-class, which would be quite dangerous).  We will be seeing its effects over the next few days. Stay tuned!

Update: People in the northern latitudes should see an auroral display tonight (Monday, February 14).  If you live in the northern tier of the U.S., Northern Europe, and areas north, you should keep an eye out tonight and tomorrow (Feb. 15).


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