On Sunday, April 23, at night, the northern lights could be seen at very low latitudes near the Earth’s equator, very far from the usual polar environment. The photogenic spectacle was recorded in unusual places such as Texas or Extremadura, where it was captured by astrophotographer Lorenzo Cordero, an image selected as the best of the day by NASA. “Simply, it is due to one of the largest magnetic storms that has occurred in recent years, caused by a solar filament,” he explains. Consuelo Cid Tortueroresearcher at the University of Alcalá de Henares and principal scientist at the National Space Weather Service (SeNMEs).
The phase known as sun peak maximum appears to have been a year ahead of schedule, according to physicist Scott W McIntosh, director of the US National Center for Atmospheric Research (NCAR). Along with your registration sunspot proliferationMcIntosh relies on information his team has collected over 20 years of collating historical data from the solar intensity since 1750. Everything indicates that the intensity peak will arrive at the end of 2023 or the beginning of 2024, which would mean a “event terminator”, according to the American scientist. that phenomenon terminator It happens when the usual solar cycle —which lasts 11 years— ends abruptly, changing the polarity of the star, and the new cycle begins with more intensity. As one solar cycle ends and the next begins, the Sun can experience huge collisions of magnetic fields that result in gigantic plasma tsunamis that can be charged on the surface of the star for weeks.
the geophysicist Joan Miquel Cake confirms that we are indeed in a more active solar cycle than expected for the time, according to forecast estimates from the previous solar model, and draws a comparison with inhabiting “a seismic zone”: “There may be more activity, but not all the events are critical”, reassures Torta, director of the Ebro Observatory (CSIC). In 2012, for example, a powerful solar ejection was observed, but it did not reach Earth. For Cid, we are “on the way to reach” a solar peak, although he qualifies: “The worst part is the descending part of the cycle, which is when there are many filaments in the Sun.” These filaments that Cid talks about are bulges that can eject solar material into space, which pose a danger if they are oriented towards our planet. The fact that there are a greater number of sunspots means “more activity and that the probability of something happening is greater,” says the scientist at SeNMEs, a center founded in 2014 that offers daily reports and alerts in the event of extreme events related to solar activity. .
The citizen does not have to worry about the critical vulnerabilities of large infrastructures. “But it’s what keeps me up at night,” McIntosh is honest. “Someone has to be responsible in case the electrical network is damaged by a solar event and the water cannot be treated, that is important,” says the physicist.
Torta, an expert in geophysical security, categorizes solar flares at its maximum as “events with little probability, but with a very high impact”, due to the possibility of causing problems to the electrical network or to satellites. “When this center was founded100 years ago there was talk of cosmic physics to study the Sun-Earth relationship”, points out the scientist, thus describing how the public’s appreciation of its galactic ecosystem has changed.
The change in perception regarding space, and the human relationship with the cosmos, is due to the increase in satellites and electrification. A reality that forces us to pay much more attention to solar flares, since “these phenomena began to affect our technological systems, the infrastructures that we have been developing, and hence our dependence,” says Torta. A development that comes “from the 19th century with the telegraph, and now it has gone further,” she sums up.
system vulnerability
All the scientists consulted mention the Carrington event as the biggest solar storm —by Richard Carrington, the astronomer who documented it—, when in 1859 an extremely powerful flare scorched the telegraph network of the time in the United States and the United Kingdom, while the night fell. He returned day in the Caribbean, Hawaii or the Canaries. Another iconic event occurred in 1989 in Quebec (Canada), where the lightning strike knocked out a hydroelectric plant and “Millions of people were left without power for 12 hours”, recalls Miguel Herraizprofessor emeritus at the Faculty of Physical Sciences of the Complutense University.
The leap from 200 years ago to contemporary techno-scientific society causes new dangers due to system overload: the drop in radio emissions, GPS navigation or communication satellites. “Geomagnetic storms have a great influence and in situations of very high electrical conductivity they disturb the equipment”, describes Torta, for whom there is now greater awareness regarding the protection of critical infrastructures. “The destruction of an electrical node could be a catastrophe, it would be equivalent to months of work due to the difficulty of replacing the parts,” Herraiz details.
The geomagnetism expert from the Ebro Observatory explains: “We must not dramatize, nor do we have to become paranoid, but it is advisable to analyze the extent to which we are vulnerable.” Torta points out that for an “extreme event” to occur, many extraordinary coincidences must occur: “Not only that the ejection catches the Earth in the middle, but that the magnetic field associated with that plasma that travels with the solar wind, has a polarity that it is contrary to that of the terrestrial magnetic field so that a phenomenon called magnetic reconnection occurs, which is the one that commands, and that is complicated ”.
The researcher suggests that each country needs to “know its electrical network, as well as analyze how dependent it is on its technology.” All in all, the geophysicist celebrates that society has also become “more resilient to climate phenomena”, as well as technology, since transformers or satellites are not like those of the 1970s.
southern auroras
The Earth is completely subjected to the activity of the Sun and when it reaches violent levels in the form of eruptions or solar flares (solar flares, in English) increases in radiation and emissions of extremely energetic particles are generated that directly affect our planet. Regularly, when a large mass of plasma from the Sun impacts the Earth, the solar wind causes geomagnetic storms in the upper layers of the atmosphere. In space weather, its most colorful manifestation is usually known as the northern lights, visible in the strip of the north and south poles of the planet.
But if the storm is strong, the auroras can be visible in lower latitudes that, as weeks ago, include the Iberian Peninsula. The peak of the solar cycle, which causes much more material to be ejected from the star to the Earth, is what has caused them to be observed in the southern United States and Europe, places that are rarely used due to their proximity to the Earth’s equator.
For Professor Herraiz, the increase in boreal sightings helps to talk about the “geophysics of Earth’s space environment”. A key aspect in this matter is the early detection of space weather phenomena, which may allow the adoption of preventive measures to reduce damage from extreme solar events. Something that the physicist considers vital: “The more science there is, the better information we will have and the prevention will be more precise.”
“The aurora is the most striking manifestation of the magnetic storms caused by the mass that comes from the Sun and impacts the Earth”, synthesizes Maria Teresa del Río Gaztelurrutia, from the Planetary Sciences team of the University of the Basque Country (UPV/EHU). Physics clarifies that they are common events, and that only when they are “bestial events” can they cause problems. That causes the sky to glow unusually at twilight with purple, violet and purple tints as electrons and protons collide with Earth’s oxygen and nitrogen.
He astroshow that can be seen in the twilight sky is the “friendly face”, says Herraiz. Aristotle, Seneca and Pliny the Elder already spoke of inexplicable celestial lights in the texts of their time, “which makes it possible to think that the auroras had already been observed in our latitudes and that these atmospheric phenomena are as old as the world,” says Herraiz. , “only now we record them better.”
“What is contemplated is a consequence of the impact of a coronal mass ejection [CME, por sus siglas en inglés] that has traveled from the Sun to the Earth’s magnetosphere and the interaction of high-energy particles dragged by the disturbed solar wind, which have penetrated our planet’s atmosphere”, explains Herraiz. The light emitted by these particles when losing energy produces this symphony of colors that we call auroras, but it also shows physical phenomena that occur on an atomic scale. This interaction “makes clear the existence of our atmosphere and the Earth’s magnetic field and, in a certain sense, makes it visible”, emphasizes the professor emeritus, and normally “it does not have in itself any danger”.
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