THE SUN IS STILL SHOOTING AT US
GEOMAGNETIC STORMS ARE POSSIBLE THIS WEEK: Yesterday, a magnificent CME billowed away from the sun's eastern limb. A glancing blow from that CME combined with influences from an incoming solar wind stream could cause G1/G2 geomagnetic storms on Nov. 6th and 7th.
THE STRONGEST SOLAR FLARE OF THE SPACE AGE: Twenty-two years ago today, the sun unleashed the strongest X-ray solar flare of the Space Age. The underlying sunspot was not facing Earth; otherwise we might have experienced a new Carrington Event. Instead, the debris flew harmlessly off the sun's western limb:
The flare's extreme ultraviolet flash. Credit: SOHO
The explosion on Nov. 4, 2003, was so intense that, at first, no one knew how strong it was. X-ray detectors onboard GOES satellites were saturated for 11 minutes. This clipped the readings at X17.4, but clearly it was stronger. Shortwave radios in North America went silent as the continent experienced a deep radio blackout--a hint at the flare's true severity.
Eventually, researchers figured it out. Our personal favorite estimate comes from this paper, which describes how Earth's ionosphere was used as a giant solar flare detector. Their answer, X45, has been confirmed by other studies.
This puts it in the same ballpark as the Carrington Event. There were no X-ray detectors in the 19th century, so researchers have to use indirect methods to estimate the intensity of Carrington's flare on Sept. 1, 1859. Studies of auroras, ice cores, and magnetic disturbances suggest values near X45, although some estimates go as high as X80.
Now for the interesting part: The Nov. 4, 2003, flare occurred during the declining phase of Solar Cycle 23. Twenty-two years later, we are near the same point in Solar Cycle 25. As any good space weather forecaster will tell you, the downslopes of solar cycles are prime time for big explosions. No one knows why, but it's true.
In conclusion, don't be surprised if it happens again.
