Solar flares to cause geomagnetic storms for Halloween – experts

Countries from Canada to Australia to the south-east US are on alert for major disturbances that could disrupt communications systems and power grids

A major geomagnetic storm watch has been issued this Halloween because of a radiation blast emitted by an explosion on the sun, with countries including Canada, Australia, south-east US, New Zealand and Taiwan on alert for massive disruptions to communications systems and power grids.

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The report from the National Oceanic and Atmospheric Administration (NOAA) says that the sun’s C-class flare – the strongest category of solar storm – took place at 4.45pm BST on Thursday (2.45am ET on Friday) at the lower part of the sun’s atmosphere, the chromosphere.

It was a C-class event – the weakest of the four types of solar storms – and means the CME – the zone of the sun most prone to eruptions of radiation – was north of Earth at the time of the blast.

The flare was observed by NOAA’s Solar Dynamics Observatory, which tracks the sun in infra-red wavelengths, and by a Space Weather Prediction Center crew based at NOAA’s Space Weather Prediction Center in Boulder, Colorado.

“We expect this flare to reach Earth on or before October 31,” Tom Berger, the center’s director, told the Associated Press.

NOAA’s warning doesn’t specify possible effects but an earlier report warned that it could trigger serious disruption to technology systems in the space-to-ground communications and power grids.

Solar storms cause blackouts and radio blackouts. Severe solar flares in the 1950s affected long-haul communication lines and expensive electric motors, prompting the US government to launch the world’s first satellite-based radio communications network to harness the aurora borealis, commonly known as the northern lights.

Sun flares typically generate a huge X-ray flare that can disrupt cellphones and high-frequency radio transmission systems across millions of square miles. Smaller X-class flares are not as damaging, but can cause changes in GPS signal strength and radio. Even weaker X-class flares can disrupt power grids, satellite systems and other electronics, like those in smart power meters that use radio frequency frequency signal.

CMEs have similar effects. Thermometers in East Sussex, near Bristol, recorded the aurora borealis at record levels on Monday evening, as high as 77km (45.7 miles) in the atmosphere, according to the UK Met Office, before fading away and settling to only 10-15% of normal levels.

“A strong aurora borealis could be seen across the British Isles last night,” said Nick Dunlop, a meteorologist at the Met Office. “It was quite dramatic.”

Berger said the strongest solar storms may produce a coronal mass ejection, which would be a cloud of solar material with thousands of miles of solar wind, known as a geomagnetic storm.

A large storm could affect the United States, but thus far its experience with geomagnetic storms has been relatively mild. The states of North Carolina and South Carolina were hit by one in 2013 when the orbit of the Earth’s moon pulled in geomagnetic winds at high-altitude – the area usually most susceptible to geomagnetic storms.

The northern and southern hemispheres are heavily affected by Earth’s electric grid. A 1991 storm dropped 500Mbps into Canada’s voltage levels, but the effect on the US, which was not affected at the time, was thought to be negligible.

A Canadian geomagnetic storm that struck in 1997 delivered 988Mbps to South Africa’s voltage levels, but again scientists said it would have been ineffective in the US.

Geomagnetic storms are made worse by the way Earth’s magnetic field is tilted compared to the Sun’s magnetic field. The tilt means that the Earth’s magnetic field collects particles from the Sun while the Sun’s magnetic field attracts solar particles swirling over the solar disk. When solar waves are travelling in opposite directions, they are constantly colliding to create geomagnetic storms.

However, the UN has warned that without an international system for sharing information and predicting the effect of solar activity, Earth would be in danger of being blindsided by such events and suffer damage that would be irreversible.

The warnings come as the solar system is moving rapidly towards a period known as the end of the solar minimum, which is a peak in solar activity. Scientists have warned that that since 2008 solar activity has been far below its average.

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