This week a mild Coronal Mass Ejection off the sun blasted past Earth. It was only a mild CME with solar winds at 500km per second, which is a medium kind of speed. The experts were all predicting a G1 class Geomagnetic storm, and were a bit astonished when we got much bigger G3 storm instead. (NOAA’s G scale runs from G1 up to G5).
This occurred near the minimum weak point of the solar cycle, and we’re going to get much bigger blasts as Cycle 25 ramps up. But if mild CMEs can rattle the Earth’s magnetic field this much, things might get much more exciting when moderate or strong CME’s shake the cage. Satellites and networks could be in trouble. “Grid’s Away”…
Is Earths magnetic field weaker or more vulnerable than we thought? How could we miss that?
“Nobody saw the KP Index hitting 7.
…when I say nobody, I mean nobody predicted this: not NASA, NOAA, ESA or IPS in Australia.”
It was not dense, and the filament released was hardly cause for concern.
“There is absolutely nothing in the history of space weather that advises the expectation of a strong geomagnetic storm off a mild CME produced by the eruption of a small plasma filament,” says Ben Davidson of SpaceWeatherNews.com.
What happens when the next one hits on the heels of a coronal hole stream?
Or if the filament was bigger?
What happens when that X-class solar flare is launched in our direction?
According to NOAA a G3 storm is a “strong” one, with a Kp of 7, and can be expected to cause this kind of disruption.
Spacecraft operations: Surface charging may occur on satellite components, drag may increase on low-Earth-orbit satellites, and corrections may be needed for orientation problems.
Other systems: Intermittent satellite navigation and low-frequency radio navigation problems may occur, HF radio may be intermittent, and aurora has been seen as low as Illinois and Oregon (typically 50° geomagnetic lat.).
Questions for readers: I would think we would have very accurate readings of Earth’s magnetic field, so wonder what it is about this that meant the experts got surprised? Are there some components of the whole field that we don’t record well, or didn’t think mattered? Perhaps the solar wind hit at “just the right angle”? Is this just a one off event, amplified for some reason we don’t understand, or is it a sign of things to come.
Thanks to Sophocles.