2024-08-22 04:00:08
By Elisa Robert and Mathieu Barth̩lemy РGrenoble Alpes University (UGA)
Despite the 150 million kilometers that separate it from Earth, the Sun does not only illuminate us: it can also have effects on our electricity networks, and even on transport.
The Sun, as well as its influence on Earth, are studied by a science called space meteorology. The latter studies the complex interactions that occur between the Sun, the Earth and its magnetic field. The goal is to understand, but also to quantify, and if possible to predict, the impact of the Sun on our space and terrestrial infrastructures. But then what are these risks? How can the Sun affect our human activities? And above all, how can we predict them and protect ourselves from them?
NASA, Aaron Kase, Medium69/Wikimedia, CC BY-SA
The benchmark event in space weather is the so-called “Carrington Event.” In 1859, northern lights were observed at very low latitudes (as far as Cuba), while these phenomena are normally located in the polar regions. At the time, technology was almost exclusively limited to the use of telegraphs, and it was these that recorded disturbances during this event. In fact, they continued to send information even though they were switched off: they were called “celestial batteries”, because it was the electric fields caused by the auroras that “powered” the circuits.
Other historical events are also worth mentioning, such as that of 1989, where the Quebec found itself without electricity for several hours, or even the Halloween storm of 2003, where the city of Malmö in southern Sweden suffered the same consequences. The cause: solar storms and their interactions with our planet Earth.
How does the Sun interact with the Earth?
The Sun is constantly sending us a electromagnetic radiation but also particles called the solar wind. These particles are mainly electrons and protons. When large solar flares occur, large quantities of plasma (made up of charged particles) are ejected: these are coronal mass ejections. When these are emitted towards the Earth, they will first encounter the Earth’s magnetic fieldwhich acts as a shield protecting us from these particles. However, these particles sometimes manage to penetrate this protective barrier to interact with our upper atmosphere. This is what we call geomagnetic storms.
It is this encounter of charged particles with molecules and atoms in the upper atmosphere (such as oxygen and nitrogen) which is at the origin of the luminous phenomenon of polar auroras. These auroras are therefore the witness visible to the naked eye that this interaction Sun-Earth does indeed exist.
The major difficulty scientists face today is that these coronal mass ejections are difficult to predict. It is therefore difficult to know when they will occur and whether or not they will have an impact on the Earth. However, we know that the Sun’s activity follows a cycle of approximately 11 years with a peak of maximum activity in the middle of the cycle. It is during this period of maximum activity that we observe the most solar flares. We are currently experiencing the peak of activity of the current solar cycle, the maximum of which is expected for 2025.
Beyond this cycle, the presence of so-called “active” regions is a marker of the greater or lesser probability that the Sun will emit such a flow of particles. They are called sunspots, because in visible light, they appear darker than the rest of the solar disk. Such a spot must also be facing the Earth for the particles it emits to reach our planet.
Solar maximum and observations of northern lights at low latitudes: this is reminiscent of recent events. On May 10, 2024, we were indeed able to observe the northern lights as far as France. And it is indeed several coronal mass ejections emitted in the direction of the Earth which are at the origin of these auroras.
Concretely, what are the effects on Earth?
There are several. The sectors of activity concerned are numerous and the systems are concerned in different ways. A first example can be given with the electrical networks which are impacted by what are called geomagnetically induced currents, created by geomagnetic storms. These currents are added to those already present in the conductors, leading to disturbances, and sometimes even to the blackout of the networks. But the electrical networks are not the only ones concerned, pipelines and the railway network are also. Another example that can be given concerns aviation. This sector can be impacted by the high-energy particles that are sent by the Sun during coronal mass ejections. Indeed, these particles can directly penetrate the systems of aircraft and cause temporary or permanent damage. These same particles can irradiate the passengers and crew members of an aircraft in the event of a major geomagnetic event.
Another example that can be given here concerns the devices of our daily life. Mobile phones, smart watches, our cars and many others, all use satellite positioning systems (such as GPS or its European equivalent Galileo) to be able to geolocate themselves. These systems can be disrupted by geomagnetic storms, leading to accuracy errors and position shifts ranging from a few meters to several hundred meters, which can be very problematic.
The radiation emitted by the Sun during periods of high activity can have many consequences on our terrestrial systems.
ESA/Science Office, CC BY-SA
Similarly, satellite communications and high-frequency communications are also impacted by geomagnetic storms, but also by bursts of solar radiation. Consequently, sectors such as maritime transport, the military and finance are also disrupted by these events.
Adapting our societies to better prevent solar storms
These various disruptions can have serious economic and social consequences, also leading to cascading reactions, given that all our systems are interconnected. Therefore, if a electrical network is out of service, all the systems dependent on these networks will also be, leading to direct consequences on the infrastructures, but also on our daily lives. This raises several questions: are we aware of this risk? how to react if our technological devices no longer work for several hours or several days, or worse, if a region is deprived of electricity for a long period? All these questions are crucial, and are taken seriously by the space weather community, but also by governments, which are developing solutions to prevent these risks and minimize the damage. It is in particular this prevention and the good prediction of NOAA, the American agency responsible for observing the atmosphere and oceans, which allowed operators to limit the damage during the event of May 10, 2024. However, if the damage was limited this time, the consequences may be different during a future solar flare that is more severe or unpredictable by scientists. This would not give operators time to put in place security measures, leading to damage that would certainly be much more significant.
All these questions are currently being closely analyzed through a study financed by Axa insurance. The goal is to raise awareness of these space weather risks in the insurance industry and the rest of society, in order to better understand them, better predict them, quantify their consequences and minimize them. So, in the same way that we watch the weather forecast to know what the weather will be like, scientists consult specialized bulletins and applications informing them of upcoming solar storms. Perhaps soon we will all have alerts on our phones when a solar storm is approaching.
To go further, you can listen what a podcast produced by the Grenoble Observatory of Universe Sciences.
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