RUSENG

28 January 2019, 10:00 UTC

The largest solar flare of the past year has occurred on the Sun

Solar flare, 26 January 2019. Image taken by the AIA telescope on the satellite SDO.

The largest solar flare over the past year was recorded on Saturday, 26 January 2019. The event lasted for about 22 minutes. The maximum energy release occurred at 16:22 MSK. During the event, at the level of the Earth’s orbit, a flux of a soft x-ray radiation, in approximately 15-fold increase, was recorded. From the classification’s point of view, the event refers to a score of C5.0, which is the medium level on the 5-point scale, including the following stages: A (the weakest level), B, C, M and X (flares of the highest power). The last time a larger event was observed on 7 February 2018, when a flare of the level C8.1 was recorded.

In absolute value, the event does not pose a threat to the Earth and is noticeable, first of all, against the background of the general extremely low activity of the Sun over the past 1 - 1.5 years. So, for the whole of 2018 only 13 flares had occurred on the Sun, that is, in average, one flare per month. For comparison, in 2017, the Sun produced 10-20 flares per day in some periods. Such low activity is now associated with another minimum activity period which the Sun is going through now, which is predicted to end in the second half of this year, after which the flywheel of solar flares will again begin to unwind to its usual strength.

Despite the tempting opportunity to relate this solar flare to the start of a new cycle is not correct. According to modern physical concepts, flares of a new cycle should occur at high solar latitudes, at a considerable distance from the equator. Solar flares of the old cycle, by contrast, always occur near the equatorial line of the Sun. A simple study of the “geography” of the flares shows that this one is the last strong flare of the passing cycle. This is evidenced by a more detailed analysis based on the study of the structure of magnetic fields in the region of flares. This structure, like the fingerprints, clearly indicates to which of the passing or new cycle the flare is referring to.

In addition to the growth of x-ray radiation in orbit, which has already ended, no other noticeable consequences for the Earth are expected. Although class C solar flares can affect the Earth, however, this refers to larger events reaching levels form C8 - C9, whereas in this case, class C5 was recorded. In addition, the flare occurred in remote, from the Sun-Earth line, location which reduces the possibility of having an impact on the Earth's magnetic field. In all likelihood, it will take at least another year to wait until the flare activity begins to influence the Earth again, till the unfoldment of a new cycle. In the meantime, the main cause of magnetic storms on Earth remains the solar wind, as it was very recently, on the 25th of January, when at the moment the last magnetic storm was recorded.