Space agencies are monitoring the evolution of the powerful solar flare emitted by our star on Tuesday, November 11, the most intense one observed so far this year. According to the US National Oceanic and Atmospheric Administration (NOAA), it is "likely the most intense of the current solar cycle."
As a result of this solar flare, a coronal mass ejection (CME) has occurred, traveling at an estimated speed of about 1,500 kilometers per second, expected to reach Earth between Wednesday and Thursday. Its effects could last for hours or several days.
The European Space Agency (ESA) explained in a statement that the geomagnetic storm generated by this intense solar activity is "severe" and "could affect satellites, power grids, and navigation systems." However, it clarifies that this phenomenon does not pose a direct risk to people on Earth.
Solar flares are classified into five types: A, B, C, M, and X, with class X being the most powerful. The number following the X describes its intensity. The solar flare generated on November 11 is classified as X5.1, even more intense than the two previous ones that occurred in the same solar region, designated as 4274. The two previous flares were classified as X1.7 (on November 9) and X1.2 (on November 10).
According to NOAA, a solar flare of magnitude X5.1 "during the solar maximum or near the maximum is not common, but not unusual."
Solar surface activity generates phenomena that propagate throughout the Solar System. This activity is studied in cycles lasting approximately 11 years. Since these studies began in 1700, we are currently in cycle number 25, which started in December 2019. Our star is in a very active phase. During periods of high magnetic activity, such as now, geomagnetic storms that potentially affect space and terrestrial infrastructures, and astronauts aboard the International Space Station (ISS), about 400 kilometers from Earth, can occur.
In May 2024, the most intense geomagnetic storm of the last two decades occurred, classified as a G5 storm, on a scale that quantifies intensity and effects, ranging from G1 to G5.
As explained by ESA scientists, "when a solar flare occurs, the explosion can release as much energy as a billion atomic bombs. A stream of electromagnetic waves leaves the Sun at the speed of light and reaches Earth eight minutes later, potentially interfering with shortwave radio transmissions and causing errors in navigation systems." A solar flare is usually accompanied by a large eruption of ionized gas from the Sun's outer atmosphere, known as a coronal mass ejection (CME). A CME creates bursts and shock waves in the solar wind, which, if directed towards Earth, can take between 18 hours and several days to reach us.
When a coronal mass ejection (CME) reaches Earth, it disrupts its magnetic field, causing a geomagnetic storm. These storms, according to ESA, can affect long metal structures on Earth such as power lines and pipelines, as well as satellites in low orbits, although there are safety measures that can be applied to minimize potential damages from solar activity.
The positive side of these events is that they often also generate spectacular auroras borealis in the northern hemisphere and auroras australis in the southern hemisphere of Earth. If they are very intense, as in this case, these auroras can be seen at lower latitudes than the poles.
During the major solar storm of May 2024, auroras borealis were even observed in some areas of Spain, and also last night this phenomenon was visible in some areas of our country, such as at the Calar Alto Astronomical Observatory in Almería.
To anticipate the potential damages that solar activity can cause, several space observatories continuously monitor our star, such as the Solar Orbiter spacecraft -a mission by ESA in collaboration with NASA-, SOHO -also by NASA and ESA- or the Solar Dynamics Observatory (SDO) by NASA. Additionally, new probes like Vigil, scheduled for 2031, are in progress to enhance early detection of these events.