Strong Solar Flare From Sun's Heart-Shaped Sunspot Temporarily Disrupts Radio Communications

While they make for stunning images, solar flares could also disturb the atmospheric layer where GPS and communications signals travel.

NASA’s Solar Dynamics Observatory captured images of a mid-level solar flare at 8:29 p.m. EDT last April 17. A loop of solar material was seen emanating off the sun’s right limb.

An awe-inducing solar event, solar flares are potent bursts of energy radiating from the surface of the sun. Once these intense energy beams hit Earth, they can interact with the planetary magnetic field and atmosphere, producing lights at the north and south poles.

It is yet to be known exactly what causes these flares, but it has been proposed that the process of magnetic reconnection occurs and converts magnetic energy into light. This prevailing theory obtained evidence in the form of high-resolution images of an eruption in 2015, the most detailed image seen of the formation of these events.

This recent flare led to “moderate radio blackouts” during its peak. Such blackouts only take place during the course of a solar flare, which means they have already subsided and are no longer a cause for worry. They are also unlikely to have a major impact on the planet.

The Space Weather Prediction Center defines a radio blackout as the lack of capability to communicate on high-frequency bands in the 5 to 35 MHz spectral range. Lower frequency radio communications, though, may also be substantially affected during radio blackouts.

Here’s how it happens. X-rays and extreme UV light from solar flares ionize the planet’s atmosphere, causing the sun-facing ionosphere to be enhanced, which then blocks radio signals normally reflected off this atmospheric layer. When radio waves are successfully reflected off the ionosphere, long-distance radio communication pushes through – thus no radio blackout occurs.

This flare is classified as an M6.7 class flare, where flares of this class are one-tenth the size of the most intense ones dubbed as the X-class flares. The number pertains to its strength, where an M2 is twice the intensity of M1, and so on.

The flare hailed from Active Region 2529, an area of intricate magnetic activity on the sun. The active region sported a sunspot over the last few days, changing in size and shape as it gradually made its way across the sun’s surface over the last week and a half.

The sunspot, which rotated out of earthly view over the sun’s right side by April 20, was large enough to be seen from the ground without being magnified, and even at some point big enough that nearly five Earth-sized planets could fit inside. A study of this phenomenon helps scientists better probe what leads sunspots to erupt alongside solar flares at times.

“Ever since a solar flare was first detected by Carrington and Hodgson in 1859, this spectacular phenomenon of solar activity has been a subject of intense research and has served as a natural laboratory for understanding the physical processes of transient energy release throughout the universe,” writes Ju Jing, a physics researcher out of New Jersey institute of Technology, in her recent paper.

She says, for instance, that large, ground-based telescopes can possibly measure these solar features “down to their fundamental spatial scale,” which can be coupled with theoretical models to fully understand how solar phenomena impact Earth.


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