The Sun is a huge ball of gas that, however, is not always in the same state: scientists have discovered that its activity increases and decreases. And it does not do so erratically, but the maximum and minimum occurs once in each solar cycle, a period lasting approximately eleven years. At this time, at its peak, the Sun’s magnetic poles invert and our star goes from a calm state to an active state, conducive to solar storms.
Well, NASA, the National Oceanic and Atmospheric Administration (NOAA) and the International Solar Cycle Prediction Panel have announced that the time has come: We are at the solar maximum of the current cycle. A phenomenon that will last until next year, as explained by the experts in a statement.
But how do we know we are at solar maximum? The spots that astronomers observe on the surface of our star hold the key: scientists track the number and surface of these spots to determine and predict the progress of the cycle and, ultimately, solar activity. Although it may sound counterintuitive, sunspots are cooler regions of the Sun caused by a concentration of magnetic field lines. These points are the visible component of active regions, areas of intense and complex magnetic fields that twist and burst, and which are the source of solar flares.
On the left, solar minimum without spots; On the right, image of our Sun at a solar maximum, where sunspots can be seen
“During solar maximum, the number of sunspots, and therefore the amount of solar activity, increases,” explains Jamie Favors, director of the Space Weather Program at NASA Headquarters in Washington. “This increase in activity provides a great opportunity to learn about our nearest star, but also causes real effects on Earth and throughout our Solar System.”
On the left, image of the Sun with extreme ultraviolet light in a period of solar minimum; On the right, the same image but taken in a period of solar maximum, where you can see the arcs produced by the activity of the solar magnetic field
The consequences of reaching solar maximum
Solar activity strongly influences the conditions of space: it is what is known as space weather. Among the phenomena that occur on the Sun, one of the most affecting are coronal mass ejections, in which the Sun sends jets of strongly charged particles that, although they do not directly affect life on Earth, if they collide with our magnetic field, which is a kind of invisible ‘doughnut’ around our planet and generated from the core. With these impacts, it is deformed at its poles (or where the ‘hole’ of the magnetic donut would be) by the action of the radiation emitted by the Sun.
This energetic jet collides with the oxygen and nitrogen atoms of our magnetic field, deforming it and emitting the characteristic greenish and purple colors near the ‘hole’ of the donut, known as the northern lights. But, in times of strong solar activity, as has been happening in recent months, these colorful phenomena can be observed in latitudes far from the poles, as happened last May, when they were sighted auroras from Spain and other points in the world closer to the equator.
Although they do not affect terrestrial life, they can damage satellites, spacecraft – even the astronauts themselves if they are currently on a spacewalk -, communications and navigation systems (such as radio and GPS) and electrical networks. on Earth.
The most powerful solar storm ever recorded It is known as the Carrington event, discovered by Richard Carrington in 1859. The Earth’s magnetic field was completely deformed, allowing the entry of a solar flare that caused immense northern lights and outages in the incipient transoceanic telegraph network.
The ‘worst’ is yet to come
However, having reached solar maximum does not mean that we are also at the peak of solar activity. “While the Sun has reached maximum solar period, the month in which solar activity peaks will not be identified for months or years,” explains Elsayed Talaat, director of space weather operations at NOAA. That is to say, that the ‘worst’ is yet to come.
So when will our star reach its peak of activity? Short answer: we don’t know. Long answer: Scientists cannot determine the exact peak of this solar maximum period for many months because it is only identifiable after they have tracked a steady decline in solar activity after that peak. However, it is known that the last two years have been part of this active phase of the solar cycle, due to the constantly high number of sunspots during this period. That’s why experts anticipate that the maximum phase will last another year or so before the Sun enters the decline phase, which leads back to solar minimum.
The amazing cycle 25
However, although each cycle is unique – some cycles have longer and shorter peaks, and others have smaller peaks that last longer – this one in particular (number 25 since records began, back in the 17th century, when Galileo first observed sunspots) is proving very challenging: solar astrophysicists predicted it would be quiet, just like the previous two, and showed signs of the complete opposite from the beginning.
Furthermore, the solar maximum was prefixed for last yearbut it has finally gone ahead, as some experts already suspected. “Solar cycle 25 sunspot activity has slightly exceeded expectations,” said Lisa Upton, co-chair of the Solar Cycle Prediction Panel and senior scientist at the Southwest Research Institute in San Antonio, Texas. “However, despite seeing some large storms, they are no larger than we might expect during the peak phase of the cycle.”
The most powerful flare of the solar cycle so far was an X9.0 on October 3 (the X class indicates the most intense flares, while the number provides more information about their strength). NOAA anticipates additional solar and geomagnetic storms during the current period of solar maximum, creating aurora viewing opportunities in the coming months, as well as potential technological impacts. Additionally, although less frequently, scientists often see quite significant storms during the waning phase of the solar cycle.
Understand the solar cycle
Although much progress has been made in predicting space weather, there is still much work to be done: predictions need to be refined and there are questions such as why the solar wind is accelerating in a way that scientists still do not understand.
Therefore, missions like Parker Solar Probefrom NASA, or Solar Orbiterfrom the European Space Agency, are approaching the Sun (in the case of the first, in December it will make the closest approach ever made by human technology; and in the case of the second, it will photograph the poles of our star for the first time ) will help in the task of unraveling its mysteries.
And, even though space weather has its dangers, experts send a reassuring message: “Don’t be worried, but be prepared. And that’s what science is for. “We cannot control nature, but we can understand it,” Javier Rodríguez-Pacheco, a professor at the University of Alcalá de Henares (UAH) and an expert in solar astrophysics, told ABC. «If appropriate measures are taken, its harmful effects will be mitigated. And, in fact, governments and space agencies are already doing it.
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