RUSENG

February 1, 2019, 08:10 UTC

Magnetic storms on the Sun start to repeat in every 27 days

Magnetic storm 1 February 2019.

A weak magnetic storm, which became the third this year, was recorded today, 1 February 2019 between 1 and 2 am, MSK. The event belongs to the lowest first class on a five-point scale and should not cause any noticeable changes in the geomagnetic environment or the operation of satellite systems. During the day, individual disturbances of the magnetic field can be observed, but, the probability that they once again reach the storm threshold, is less than 10%.

In connection with the Sun going through the minimum of the solar cycle, the configuration of its active centers had been extremely simplified. Currently, the main source of geomagnetic disturbances are two coronal holes (regions with open magnetic field lines along which the solar plasma can flow out into interplanetary space) located several tens of degrees from each other. Due to the rotation of the Sun, these areas appear on the eastern edge of the Sun (located on the left, viewed from the northern hemisphere of the Earth), then pass through the central meridian, located opposite the Earth, and then, again, goes to the Sun’s back on its right edge. When a hole passes through the central meridian, the plasma flowing from the Sun, hits the Earth’s magnetic field and causes its disturbance. This is exactly the nature of all three magnetic storms recorded this year, which occurred on 5 January, 25 January and today, 1 February 2019.

If you look at the dates of two storms from this list 5 January 2019 and today 1 February 2019, then it is easy to notice that the interval between them is of 27 days, that is, equal to the period of rotation of the Sun around its axis. It is easy to guess that both of these storms were caused by the same coronal hole, more precisely, by a single stream of plasma, having completed a full revolution and returned to Earth. Hence, even without knowledge of the nature of solar activity, it is not difficult to predict the date of the next storm. To do this, add 27 days to the date of January the 25th. This gives February the 20th. It was on this date that the prediction models assigned the nearest geomagnetic storm. If the structure of the solar centers does not change, then we will be able to predict dates of the storms in March. The first of them will occur on the first day of spring at the junction of February the 28th and March the 1st. The next one will happen on 19-20 March 2019.

Noticeable changes in solar activity, for example, the beginning of a new solar cycle, can break this pattern. In addition, coronal holes are long-lived, but still, are not eternal, and sooner or later, they must disappear from the solar disk. Nevertheless, for some time, at least all of the February, the Sun will remain as a very simple object for prediction.