The Sun goes Boom!

Wednesday, September 7th, 2005 at 04:57 PM by Juan

Those of you who look at the Current Solar Activity Panel on the right hand side of this page may have noticed that the Solar X-rays indicator is saying “Mega flare!” This is indication of a solar flare with an X-ray flux greater than 0.001 Watts/meter2 has occured, a very rare event indeed. In fact, the NOAA Space Environment Center released a Space Weather Advisory Bulliten stating the following:

One of the largest solar flares on record occurred today, September 07. Very active Region 808 produced a powerful X17 flare observed on the NOAA GOES satellite at [September 07, 12:40 p.m. CDT]. This flare, the 4th largest in the last 15 years, erupted just as the Region 808 sunspot cluster was rotating onto the visible disk of the sun. Intense radio emissions were also associated with this flare. A very bright and fast coronal mass ejection was observed on coronagraph imagery; however, the material was not Earth directed. … This event created a complete blackout of high frequency communications on the daylit side of Earth. Communications used by emergency services along the Gulf Coast may have experienced problems due to this flare.

Xray 5M 200509072146
As shown in the above plot of the X-ray flux versus time from the GOES satellites, it appears that at about 12:40 pm CDT (17:40 Universal Time) on September 7, there was a thousand-fold increase in the X-ray flux. This is associated with a monster solar flare and accompanying coronal mass ejection on the eastern limb of the Sun (see the photo below).

Sept7Megaflare
(Click on image for full-size QuickTime movie.)
The September 7 Megaflare captured by the GOES Satellite X-ray camera.

Since it was on the limb of the Sun, this particular explosion was directed away from the Earth and the charged particles from this flare are unlikely to hit earth and cause strong aurora. However given the rotation period for the Sun of about 25 days, in about 6-7 days this sunspot will rotate to where it is pointed more directly at earth. Therefore, in a week any similar flares will likely spark some strong aurora (and more significant radio communications problems).

Editor’s Note: This article was revised to include information from the SEC bulliten at 8:15 pm on September 7.

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