In 2024, like every eleven years or so, the Sun enters a period of maximum activity in which this large ball of gas shakes, spewing particles and matter. On Earth, these solar flares are responsible for the northern lights, but they can also disrupt communications systems and power grids.
When the Sun moves, the sky lights up and green, pink or blue streaks appear in the middle of the night: northern lights. In 2024, when the immense star enters a peak of activity, these nighttime shows could multiply.
From a distance of 150 million kilometers from Earth, the Sun continues to look the same as always: a large ball of gas that dazzles and heats the atmosphere. However, in reality, its activity varies in intensity throughout a cycle, which lasts about eleven years. According to specialists, particularly those from the United States National Oceanic and Atmospheric Administration (NOAA), the Sun is approaching the peak of activity of its current cycle, which began in 2019.
“The Sun is an enormous ball of plasma, extremely hot, formed by electrically charged particles, in rotation, linked to a magnetic field,” explains Pierdavide Coïsson, associate physicist at the Institute of Physics of the Globe in Paris.
“In a very complex dynamic, it works like a magnet and, with each new cycle, it changes direction. And this is accompanied by an increase in its activity.”
In other words, at the beginning of a cycle, everything is more or less calm on the Sun, with the North and South magnetic poles in place, but little by little, the magnetic field alters. It twists and turns… until the initial North and South poles are reversed.
“A boiling pot”
Although researchers strive to explain the exact process behind this phenomenon, the symptoms are always the same: “With magnetic instability, the surface of the Sun becomes covered with spots. “It looks like a boiling pot,” adds Pierdavide Coïsson.
In February 2021, the European Space Agency (ESA) took an image of the Sun with its Solar Orbiter probe. At that time, the surface of the star appeared homogeneous and smooth. Two years later, in October 2023, a second photo showed the Sun with large identifiable spots, a sign of a peak in activity.
“They are the foci of what are known as solar flares,” explains Frédéric Pitout, associate astronomer at the Institute for Research in Astrophysics and Planetology (IRAP). “Electrical particles and matter – called coronal mass – will be ejected at high speed towards the space”.
Most of the time, these solar flares have no impact on Earth: the elements ejected into space are sent in another direction or the flare is too weak to be perceived as far as the blue planet.
But as the Sun enters its peak activity, the risk of large solar flares increases. On Sunday, March 24, the Space Weather Prediction Center (SWPC), a US agency specialized in observing solar activity, recorded a class X1.1 eruption, one of the most powerful. A few weeks earlier, on February 23, ESA had recorded an even more powerful X6.3 class flare.
A three-active region of Soleil has recently released three class X solar eruptions, which are the most powerful.
The largest, a «X6.3» eruption occurs at 23h43 CET at the end of the night, the strongest solar eruption is never observed during the solar cycle courses… pic.twitter.com/uMusU443Cx
— ESA France (@ESA_fr) February 23, 2024
The shield of the magnetosphere
“And sometimes, the ejecta will be sent directly towards the exact alignment of the Earth and will have an impact,” says Pierdavide Coïsson. However, they do not collide directly. First they collide with the magnetosphere, a kind of invisible shield generated by the Earth's magnetic field.
“The magnetosphere deflects some of the elements, but electrical particles can still break through this defensive line and open the door to our atmosphere,” he continues. This is known as a “solar storm” or geomagnetic storm.
“Most of the time, the particles simply head towards the polar areas, giving rise to the northern and southern lights,” adds the specialist. “But the more powerful the phenomenon, the lower in latitude the auroras will descend.”
These nighttime shows are, therefore, the result of the interaction between solar particles and the Earth's atmosphere. And when the northern lights can be seen as far away as Europe, it is originally a sign of a large solar flare.
Risks for our infrastructure
Behind the visual delight of the Northern Lights, the Sun's activities can also hide potential problems for our electrical infrastructure and the satellites orbiting the Earth.
“Beyond their luminous appearance, the particles ejected by the Sun carry a large amount of energy. In the event of a particularly intense solar storm, they can disrupt all electrical networks,” insists the specialist.
The strongest example of this phenomenon dates back to 1859, the Carrington event, named after the British astronomer who studied it. In the mid-19th century, the entire telegraph network was interrupted when telecommunications stations caught fire due to power surges in the electrical network. As an example of the importance of this solar storm, the northern lights could be seen even in Cuba.
However, unlike 1859, today's world is crisscrossed with electrical conductors – high-voltage lines, catenaries, rails, oil pipelines, pipes – making the global electrical grid especially sensitive to the effects of solar storms.
“More recently, in March 1989, a large solar flare caused the entire Quebec electrical grid to collapse for 9 hours,” adds the specialist.
“And in October 2003, the Halloween solar storm caused power outages and problems with telecommunications networks in various parts of the world, especially in Japan and the United States.”
And the consequences of solar storms are also above our heads. “There are also risks for all satellites orbiting the Earth,” continues the specialist. “Energetic particles can disrupt your electronic systems. In 2022, Starlink, Elon Musk's company that develops satellite Internet, lost about forty satellites just after their launch, when they were in the deployment phase, due to a solar flare.
“Satellites have become indispensable for our daily lives; for example, they allow us to use GPS to locate planes and ships. They also allow long-distance communications,” adds Frédéric Pitout of Irap.
“If they were to suddenly fail, even for a few minutes, the consequences could be catastrophic.”
This specialist also thinks about the implications for space research. While astronauts on the International Space Station are protected by the magnetosphere, the same will not be the case for those heading to the Moon or, in the more distant future, Mars.
Space weather
According to a 2003 OECD study, a Carrington-like event is considered one of the worst events that could occur today, with damage estimated at several trillion dollars for the world. The return to normality would take months or perhaps years.
This threat has been driving the development of “space meteorology” for several years. Using ground-based observatories and a fleet of space probes, which constantly observe the star, researchers try to detect eruptions and warn if a major one is approaching. “But it is still very difficult to anticipate,” warns Frédéric Pitout. “When we see the eruption, we only have a few hours or a few days before we see the potential effects.”
ESA's space weather services network, managed by the ESA Space Security Programme, is the main specialized infrastructure in Europe. Although it has a series of ground sensors, the organization also works on the development of space missions such as Vigil. The goal is to provide near real-time data on solar activity before it is detectable from Earth.
Today marks #SolarOrbiter's closest approach to the Sun, giving it a front-row seat during #SolarEclipse2024 🕶️🍿
What's more, this weekend the spacecraft is 90 degrees further round the Sun compared to Earth, meaning it can watch for potentially dangerous eruptions sent in our… pic.twitter.com/4CZrC52r21— ESA's Solar Orbiter (@ESASolarOrbiter) April 4, 2024
“In any case, there are still many mysteries to be unraveled about the solar wind, but also about the functioning of this solar cycle, and that inevitably generates a lot of uncertainty,” adds Pierdavide Coïsson. “Fortunately, a magnetic storm remains a rare phenomenon, even when the Sun is at its most active.”
For their part, “all electricity companies are working to make their networks less vulnerable,” concludes Frédéric Pitout. “Airlines also closely monitor solar activity to protect themselves and readjust their flight schedules in case of risk.” However, once 2024 has passed, specialists should be able to take advantage of a lull of eleven more years to prepare for the next peak in solar activity.
Note in the original language
#Northern #lights #blackouts.. #Sun #shakes