The Sun produced its strongest flare in six years and the strongest one thus far this cycle last week. It was an X 2.8 class flare, five to ten percent of the strongest on record from November 2003, and the strongest since September 10, 2017. The Sun is getting close to reaching its highest activity point for Cycle 25, the current solar cycle. And from now on, there will be a lot more exciting events.
Radio blackouts can be caused by solar flares. Deeper, denser layers of the ionosphere surrounding our planet become ionized as a result of the flares’ intense release of ultraviolet and X-ray light. Because there are so many free electrons in the atmosphere as a result of the light, radio waves lose a lot more energy. Eight minutes after the release on December 14, at 5:02 pm UTC, the light from the recent flares reached Earth.
The Americas were at that time the part of our planet that faced the Sun. Although there were reports of radio communication interference over the United States, the effects were most pronounced in South America. Thomas Ashcraft was able to record it from the Heliotown Observatory in the United States.
“On December 14, 2023, at [5.05 pm] UT, this audio specimen was captured just as an X 2.8 solar flare was about to begin. It displays what are referred to as “slow drift bursts,” or Type II solar emissions. Two different shortwave radios, one tuned to 22.2 MHz [megahertz] and the other to 21.1 MHz, were used to record the audio. Ashcraft told IFLScience that if you listen closely—ideally with headphones—you can hear the emissions gradually drift down in frequency, first passing through 22 MHz and then 21 MHz.
Its radio frequency shifts during a Type II solar emission, showing two bands of emission and shifting from high frequencies to low frequencies at a rate of about 1 MHz per second. A weaker M-class flare from the same sunspot preceded the more recent powerful one. There was some interference, but not enough to cause a blackout, throughout the sunlit regions of the Earth at the time, which included parts of Asia, Europe, and Africa.
An 11-year solar cycle transitions from a minimum to a maximum inactivity. There will likely be more flares, aurorae, and blackouts as the current cycle peaks between January and October of 2024.