Violent geomagnetic storm breaks records
The magnetic storm that has been raging since Friday evening is the strongest in decades. And it's not over yet.
(Image: NOAA)
The strongest magnetic storm in decades began on Friday evening. It reached the highest level of "Extreme" on the five-part scale of the US space weather agency NOAA at several three-hour intervals. The scale describes fluctuations in the Earth's magnetic field. The summarized daily value A for magnetic unrest reached 280 out of a theoretically possible 400, which is the highest value since November 13, 1960 and the second highest value ever measured. Geomagnetic storms only very rarely reach strength 5, most recently around 20 years ago.
Plasma clouds deform the lines of the Earth's magnetic field
During magnetic storms, plasma clouds coming from the sun deform the lines of the Earth's magnetic field, causing the aurora zone, in which the Northern Lights are visible, to shift southwards. During the current magnetic storm, northern lights were visible as far away as the Caribbean, which last happened in 1921 and 1859. In extreme cases, very severe storms can cause satellites to lose the protection of the Earth's magnetic field and be exposed to increased high-energy radiation. Fortunately, the recent eruptions have so far not been associated with a major radiation storm, which would have exacerbated this effect. Nevertheless, there have already been reports of problems with satellite systems.
Magnetic storm has temporarily subsided somewhat, but is far from over
Power grids may experience outages during severe magnetic storms. Fluctuations in the Earth's magnetic field can induce very high currents in overland grids with long lines or pipeline systems, which can damage the systems. This last happened during a magnetic storm in 2003 in Sweden and South Africa, and in 1989 it hit the area around Montreal in Canada. The accuracy of satellite navigation systems can be temporarily limited because the very strongly excited ionosphere diffracts and attenuates satellite signals considerably more than usual. Shortwave traffic is severely disrupted, although this only affects very few applications nowadays, such as HF air traffic for transatlantic flights or radio traffic from embassies.
The current magnetic storm has temporarily subsided somewhat, but is far from over. It is expected to gain strength again soon as new shock fronts arrive from the sun, and could then reach the highest category once more. The group of spots that caused the current storm is still very active and could cause further severe eruptions at any time, which would then be on their way to Earth for around 24 hours. Things will probably only calm down when the group of spots disappears behind the edge of the Sun's rotation in a few days' time, as their eruptions will then no longer be able to hit the Earth.
(uma)
