Summary of an X-traordinary day.

09:15 – Region 2673 produced a major X2.2 solar flare at approximately 09:14 UTC (Sept 6). This is the first X-Class event to be detected since May 2015. The active region is still in a decent position for Earth directed eruptions.

X2.2 solar flare

Image courtesy of SDO/AIA

12:02 – The strongest solar flare of the current Solar Cycle (24). An extraordinary X9.3 event was observed at 12:02 UTC today. A large CME (coronal mass ejection) is now visible in the latest STEREO Ahead imagery and will likely be headed our way. 

ALERT: Type III Radio Emission
Begin Time: 2017 Sep 06 1202 UTC
Estimated Velocity: 1969 km/s
HF Radio: Wide area blackout of HF radio communication, loss of radio contact for about an hour on sunlit side of Earth.
Navigation: Low-frequency navigation signals degraded for about an hour.

X9.3 event

X-Ray flux


23:55  – The CME observed on Monday swept past Earth at approximately 23:48 UTC Wednesday evening. Minor (G1) to Strong (G3) geomagnetic storming is in the forecast for middle to high latitudes during the next 24 hours. The timing works well for sky watchers across Scandinavia, northern Europe, Canada, Alaska and the northern tier USA. 

Solar Region AR2673 and Earth on scale

Solar Region AR2673 and Earth on scale


September 7
23:25 – A strong G3 geomagnetic storm happened.

ALERT: Geomagnetic K-index of 7
Threshold Reached: 2017 Sep 07 2325 UTC
Synoptic Period: 2100-2400 UTC
Active Warning: Yes
NOAA Scale: G3 – Strong 
Potential Impacts: Area of impact primarily poleward of 50 degrees Geomagnetic Latitude.
Induced Currents – Power system voltage irregularities possible, false alarms may be triggered on some protection devices.
Spacecraft – Systems may experience surface charging; increased drag on low Earth-orbit satellites and orientation problems may occur.
Navigation – Intermittent satellite navigation (GPS) problems, including loss-of-lock and increased range error may occur.
Radio – HF (high frequency) radio may be intermittent.
Aurora – Aurora may be seen as low as Pennsylvania to Iowa to Oregon, Scotland and Ireland.

Aurora forecast

Aurora forecast


September 8
13:10 – A coronal mass ejection (CME) propelled into space by an X9.3 solar flare on Thursday reached our planet a little earlier than expected and helped to generate a Severe (G4) level geomagnetic storm. The solar wind climbed to above 700 km/s and the Bz component of the interplanetary magnetic field (IMF) pointed sharply south (-32nT) following the shock passage. Visual aurora is being reported across many locations at middle to high latitudes. Attached photo below is courtesy of Kathy Laroche from Williamstown, Ontario, Canada, Scotland.

A geomagnetic storm warning remained in place for the next 24 hours. Sky watchers reported gorgeous visual aurora. 

The following 3 shot panorama was taken in Scotland just before the climax, but you can already see the fine striations, and also the pink lower border, which is caused by nitrogen emissions where the aurora extends deeper than normal into the upper atmosphere. 

Aurora - Scotland, 00:27 UTC, 8th September 2017

Aurora – Scotland, 00:27 UTC, 8th September 2017

Let’s recap:

Over 25 M-Flares and 3 X-Flares, including the largest of Solar Cycle 24. Region 2673 gave us all something to talk about over the past week. Below is a closer look at the evolution of the monster sunspot and the enormous energy it possessed. All imagery and video courtesy of the Solar Dynamics Observatory (SDO) and SOHO/LASCO.