The combination of strong solar events has prompted the National Space Weather Prediction Center (NOAA) (SWPC) to issue a geomagnetic storm warning for today (September 16). That’s great news for those looking to see the northern lights: The predicted geomagnetic storm could cause auroras deep in the mid-latitudes (around 50°) and as far south as California, Missouri, and Oregon.
Is that the culprit? In this case, there are actually two.
First A large cloud of plasma and magnetic fields, known as a coronal mass ejection (CME), was released from the Sun during the major X-class solar flare, the most powerful class of solar flares, on September 14. The X4 .5 solar flare peaked at 11:29 ET (15:29 GMT) and was the fifth largest solar flare of the current solar cycle.
The CME released during X-Flash is currently heading toward Earth and is expected to arrive today (September 16). CMEs are carried by electrically charged atoms known as ions. When they collide with the Earth’s magnetosphere, they can cause geomagnetic storms. During these storms, the ions interact with gases in the Earth’s atmosphere and emit energy in the form of light. This light is what we see as the Northern Lights, or Aurora Borealis, in the Northern Hemisphere, and the Southern Lights, or Southern Lights, in the Southern Hemisphere.
Second – the culprit is a coronal hole on the Earth-facing side of the Sun. Coronal holes appear as dark regions in the Sun’s corona (outer atmosphere). They have a clear, monopolar magnetic field line structure, essentially allowing the solar wind to escape into space more easily. This relatively fast solar wind flow and the impact of the approaching CME led to the issuance of a G3 geomagnetic storm watch.
NOAA classifies geomagnetic storms on a G scale, which measures their intensity, ranging from G1 for minor storms to G5 for the most extreme. Strong G3 conditions are forecast for today (September 16), meaning we could be in for some real auroras, as previous “minor” G1 conditions on July 29/30 were still producing dazzling auroras across the U.S. and Canada.
Source: Port Altele
