In the current cycle, solar activity appears to have peaked in early 2014. As such, total solar activity is expected to decrease over the next 4-5 years. That trend has been in place for about 18 months now. But, just because the cycle is past peak, doesn’t mean there won’t be very active periods like the last three days. In the last three days, active regions 2422 and 2423 have produced dozens of flares with 10 exceeding the M-class threshold.
The first M-class flare launched from AR 2422 and peaked with a flux of M1.95 at 10:40AM on September 27th. After that, 11 c-class flares erupted over the next 7 hours before the next flare at M1.03. Over the next three days M-class flares continued to erupt. The largest registered M7.63 at peak.
Of all the big flares over the last several days, none have shown the clear signature in imagery of launching a CME. Only the most recent M1.19 has shown a hint of releasing a CME. In addition to the imagery, this can be seen in the flare profiles. Each has a growth and decay rate over 3. Typically flares that launch CMEs are longer duration and have lower growth and decay rates.
Did you know you can browse through the flares and see all the flux profiles, timing, and growth and decay rates in the NLN solar flare browser? It is quick and easy to scan through all the recent M-class flares, or to find the most recent X-class flare.
In this animated GIF of the most recent M1.19 flare on September 29th, it is possible to see a hint of coronal dimming:
In the frames immediately following the flare, notice the darker area just to the North and West of the launch point. This coronal dimming is the indication that a CME may have been launched. The plasma casts a “shadow” as it is between the SDO camera and the Sun. Each frame represents about 15 minutes. Within 12 hours there should be LASCO imagery that will likely show a CME. Looking carefully at the GIF, it appears the CME will not impact Earth as it will likely be mostly North and well West of the Earth-sun line.
As of this writing, there is no indication Aurora hunters should expect northern lights in the next several days. For now, enjoy the amazing display of flare activity.