Solar activity is approaching maximum, following its 11-year cycle. As a result, solar flares are repeated and become more and more intense. That of May 15, the strongest since 2017, comes from the sunspot which is responsible for the beautiful and large northern lights at the beginning of May.
During the second weekend of May, last week, many of the French population were able to admire the Northern Lights in the night sky. A very rare situation at our latitudes. The reason: a giant spot (17 times the diameter of the Earth) on our Sun. This one, called AR3664, produces powerful eruptions. When they are directed towards our planet, the flow of particles transforms into a geomagnetic storm, which increases the magnitude of the northern lights visible on the surface of the globe.
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This task has not said its last word. On May 15, 2024, the “space weather” monitored by NOAA was able to observe a solar flare of X8.7, coming from the famous spot AR3664. From 50 solar flares the most powerful ever observed by humanity, it ranks in 17th place.
Solar flares are classified on a power scale, a bit like the Richter scale. First there is a letter, which classifies the eruption into a category, then a number expressing a multiplier value. Class B flares are the weakest, then there are C, M, and X. An X2 flare is two times as powerful as an X1.
The Sun's peak activity
This level X8.7 eruption is therefore particularly powerful: it is, in fact, the strongest since 2017. It was followed by others, slightly less strong. These will not have an impact on Earth, due to the current position of the spot on the Sun in relation to our planet.
Solar activity follows a regular cycle. The number of sunspots decreases then increases, as does their intensity. Every 11 years, the solar cycle reaches its maximum; a time when solar activity is extremely powerful. The X8.7 solar flare on May 15 was the strongest of the current cycle. Because we are currently experiencing the peak of this cycle; which is about to reach its maximum between the end of 2024 and 2025.
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This explains the northern lights visible in France: the higher the solar activity, the stronger the solar storms. And the stronger they are, the more they can cause geomagnetic storms having an effect on our planet.
As we are at the peak of solar activity, these strong solar flares will recur, at different levels, in 2024 and 2025. This is the reason why the northern lights of May in France could recur in the coming months .