July 3, 2021: Now, Solar Cycle 25 has really begun. On July 3rd, new sunspot AR2838 produced the first X-class solar flare since Sept. 2017. NASA’s Solar Dynamics Observatory recorded the extreme ultraviolet flash:
A pulse of X-rays ionized the top of Earth’s atmosphere, causing a shortwave radio blackout over the Atlantic Ocean: blackout map. Mariners, aviators, and amateur radio operators may have noticed unusual propagation effects below 30 MHz just after 1429 UT.
X-flares are the strongest kind of solar flare. They are typically responsible for the deepest radio blackouts and the most intense geomagnetic storms. This is the first X-flare of young Solar Cycle 25. More are in the offing. During the previous solar cycle (Solar Cycle 24) the sun produced 49 of them. Forecasters believe that Solar Cycle 25 should be at least that active. We can therefore expect dozens more X-flares as the sun approaches Solar Maximum in the year ~2025. Solar flare alerts: SMS Text.
SOLAR FLARE CAUSES RARE ‘MAGNETIC CROCHET’: The X-flare of July 3rd did something rare. “It disturbed all of my instruments,” reports Rob Stammes, who operates a space weather observatory in Lofoten, Norway. The flare produced a radio burst, an ionospheric disturbance, a surge of electrical currents in the ground, and a deflection of the observatory’s local magnetic field. All of these are shown in the strip chart recording, below.
“This is a first in many years,” says Stammes. “The magnetic disturbance (circled in yellow) is especially rare.”
The phenomenon is called a ‘magnetic crochet.’ Radiation from the flare ionized the top of Earth’s atmosphere and caused currents to flow 60 km to 100 km above Earth’s surface. These currents, in turn, altered Earth’s polar magnetic field. Unlike geomagnetic disturbances that arrive with CMEs days after a flare, a magnetic crochet occurs while the flare is in progress. They tend to occur during fast impulsive flares like this one.