29 August 2019, 7:50 UTC
Autumn’s first magnetic storm will fall on September the 1st already
Auroras are one of the most famous expressions of the magnetic storms.
This fall, the first magnetic storm will occur on the first of September. This prediction has been based on the geomagnetic activity forecast for the coming week. The cause of the magnetic storm will be an increase in the speed of the solar wind in near-Earth orbit, which will lead to a slight destabilization of the Earth's magnetic field interacting with the solar wind. Even though this interaction occurs at rather high altitudes - from 50 to 100 thousand kilometres above the Earth’s surface (this is where the solar wind collides with the Earth’s magnetic field stretching into space), the perturbations forming over here, just like string along the lines of the magnetic field, run down to the surface of Earth. This is exactly how the process of the magnetic storm appears in its somewhat simplified form.
In general, the current year is very calm from the geomagnetic activity point of view. In total, since January 2019, only 10 magnetic storms have been registered, none of them exceeded the minimum first level on a five-point scale. Four of them had occurred in winter, from January to February, three storms - in spring from March to May, and the last three are registered in last summer. The last storm was observed just recently - on 5 August. Interesting, that the last three storms, including the coming one, are the so-called the Recurrent storms. This means that they are caused by the same stream of the solar wind, which is, due to the rotation of the Sun, periodically returns to Earth and produces disturbances of the magnetic field. So as the rotation period of the Sun as observed from Earth is about 27 days, the recurrent magnetic storms do occur in this same pace. By this criterion, in particular, they are easily distinguishable from storms caused by solar flares, which occur relatively irregular. The first of the recurrent storms of this summer occurred on 9-10 July, the second, as already mentioned on 5 August and after the 27 days the third storm should happen on the 1st of September.
Magnetic storms of the lower level are rather weak phenomena; in fact, they do not affect communications, equipment and spacecrafts. The influence of magnetic storms on biological objects and human health has been studied much less, but, in general, for the phenomenon of such strength, it also shouldn’t be noticeable. It should be noted though that this year the first of September falls on Sunday. By Monday, September 2, the geomagnetic situation should already be fully stabilized according to the forecast.
Laboratory of X-ray astronomy of the Sun, Lebedev Institute, Russia
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