The sun goes through a regular 11-year cycle, swinging between periods of dormancy and periods of activity. Scientists from NASA and NOAA have just announced that the sun has just passed its minimum, and will be ramping up in activity over the next few years, meaning that we have entered a new round of the never-ending solar cycle.
We’ve been observing sunspots of thousands of years, but it’s been only since the invention of the telescope that we’ve been able to keep records of activity on the surface of the sun. Through those centuries of observations, however, we’ve been able to note a peculiar 11-year cycle. Over the course of 11 years, the sun will have little to no sunspots, then steadily grow in activity before calming down again, all to repeat again.
Astronomers suspect that the sunspot activity is connected to the strong magnetic field of the sun. When the sun is quiet, the magnetic fields are thought to be nice and straight, stretching north-to-south like they do on the Earth. But over time, the magnetic fields wind up and bunch together, forming complex, tangled weaves that plunge in and out of the surface.
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Where the magnetic fields punch through the surface, a sunspot appears. But eventually the tangling becomes too much, and the magnetic fields snap, releasing torrents of energy – and launching furious blasts of flares and coronal mass ejections. After venting their fury, the magnetic fields resume their preferred north-south direction, and the cycle starts anew.
It appears, by observations of sunspots, that the sun passed through its absolute minimum sometime in December 2019, according to a report issued by the Solar Cycle 25 Prediction Panel, a group co-organized by NASA and NOAA.
The report is only coming out now because the sun is variable month-to-month, so it takes a good number of months before a firm call can be made.
But here we are, several months into the new solar cycle, the 25th such cycle since we’ve been keeping track.
This means that over the coming months and years, sunspots should appear more and more frequently, and solar weather – including hazardous flares and storms – will become more common, peaking in 2025.
That said, solar physicists suspect that the coming increase in activity won’t be so bad. The last few solar cycle peaks have been rather tame (for reasons that we don’t understand) and we have no reason to suspect that number 25 will be anything spectacular.
Still, even a tame sun can be dangerous. Flares and coronal mass ejections pose threats to space probes, orbiting satellites, and even electrical systems on the Earth (when they get especially nasty). But the streams of particles emitted by the sun are responsible for the aurorae in our atmosphere, so on the plus side, aurora hunters should have better light shows to look forward to in the coming years.