Extremely Powerful New Year’s Eve Solar Flare Still Causing Radio Blackouts

An enormous solar flare spat out from the sun on New Year’s Eve is still causing havoc on Earth, with radio blackouts affecting vast areas of the globe.

The solar flare emitted by sunspot AR3536 was the strongest of the current solar cycle, classified as an X5 flare, with the solar X-rays causing a deep shortwave radio blackout across the Pacific Ocean.

Four days later, the flare is still affecting the Earth, with a polar cap absorption event causing radio blackouts around the North and South Poles.

Solar flares are caused by the explosive rearrangement of twisted magnetic fields on the sun’s surface, resulting in flashes of X-rays being released as solar flares. These may also be accompanied by plumes of solar plasma in the form of coronal mass ejections.

These flares are rated based on their power on a scale of A, B, C, M and X, with each progressive class being 10 times more powerful than the last. This flare, being an X5 flare, makes it the most powerful in this solar cycle so far, beating out the previous record holder of X2.8 in mid-December.

“X-class flares are simply a measure of how powerful the solar flare is. X, being the most powerful. Each letter in the grading system is 10 times more powerful than the letter below it,” Alan Woodward, a professor of computer science and space weather expert at the University of Surrey, England, told Newsweek.

Solar flares can lead to radio blackouts as the X-rays ionize the ionosphere layer of the atmosphere. Since radio communications rely on the ionosphere to bounce signals off, ionizing this layer causes radio signals to be absorbed instead, leading to signal degradation.

The polar cap absorption event currently affecting the North and South poles is causing signals below 10 MHz to be almost completely blacked out, with signals below 35 MHz being attenuated. Polar cap regions like this one are caused by protons being accelerated by the solar flare and along the Earth’s magnetosphere towards the poles, again ionizing the ionosphere. These events can last several days after a solar flare hits the Earth and affect flights crossing polar regions. Solar flares can also cause damage to satellites.

X-class flares usually only happen around 100 times per solar cycle. The most powerful recorded X-flare occurred in 2003, at X28. The 1859 Carrington Event is thought to be the most severe flare in history.

This may not be this solar cycle’s last powerful solar flare, though. The sun is nearing the solar maximum of this 11-year cycle, at which point it will reach its highest level of magnetic activity, with more sunspots and solar weather.

“The sun is a variable star which undergoes a regular cycle of activity called the solar cycle,” Gareth Dorrian, a research fellow in space science at the University of Birmingham, told Newsweek. “During each solar cycle, the sun goes from solar minimum (where there are few sunspots and little activity) to maximum, where there are many sunspots and lots of activity, and back to minimum again. This process takes about 11 years to complete.”

The next maximum is due to occur between January and October this year.

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