The Sun has been rather inactive lately. Throughout the last few years, its flare motion has been relatively weak and sparse, according to experts. However, the things may be about to change as on May 29th was spotted emitting its biggest flare since October 2017.
This could be a sign that the star has already begun its new solar cycle and will be gradually increasing to a higher level of activity in a few years, researchers have explained.
While the Sun seems rather consistent to us here on Earth on a daily basis, throughout the years, astronomers have determined that it actually undergoes 11-year activity cycles, with a certain defined minimum and maximum.
The minimum level, marked by a minimal scale of sunspot and flare activity, is the end of one cycle and the beginning of a new one. Experts can generally foresee when this is going to take place, but it’s actually incredibly difficult to assess it to smaller than a period of a few months.
The solar cycle relies on the Sun’s magnetic field, which turns around every 11 years, as its north and south magnetic poles are switching places. Scientists do not yet know what causes these cycles, but the poles switch when the star’s magnetic field is at its weakest or solar minimum.
Now, researchers expect the Sun to switch from Cycle 24 to Cycle 25, but they do not know whether the solar minimum has happened or is about to. In 2017, NASA stated that the shift was expected in 2019-2020, but in December od 2019, NOAA’s Solar Cycle 25 Prediction Panel reduced the timeframe, noting that ‘solar minimum between cycles 24 and 25 will occur in April 2020 (+/- 6 months).’
If the Sun shows signs of action, that could be the proof that the shift has already taken place, more so with the recent flare activity.
No Threat for Earth
The flare occurred on May 29th, at 07:24 UTC (03:24 EST), with the activity depicting plasma flowing out from a group of sunspots. Those sunspots are unseen beyond the margin of the Sun, but researchers can see the intense loops as they bounce out together with solar magnetic field lines.
They compose an M-class flare, which is the second strongest flare classification. These occurrences are actually mild in comparison to other solar flares, but when they are heading towards Earth can cause radio blackouts in the polar areas and radiation storms in near-Earth space that is rather dangerous for astronauts.
This particular flare was not aimed at Earth, and, as NASA notes, it was a rather small M-class flare, reaching only M1.1 on the 10-point scale.
“It takes at least six months of solar observations and sunspot-counting after a minimum to know when it’s occurred,” NASA’s Karen Fox and Lina Tran wrote in an update. “Because that minimum is defined by the lowest number of sunspots in a cycle, scientists need to see the numbers consistently rising before they can determine when exactly they were at the bottom. That means solar minimum is an instance only recognizable in hindsight: It could take six to 12 months after the fact to confirm when minimum has actually passed.”