A “dangerous” sunspot fired an intense “X-class” solar flare toward Earth, resulting in a radio blackout across the South Pacific region.
The intense solar flare was spewed out by a newly emerging sunspot identified as AR3182, with NASA‘s Solar Dynamics Observatory (SDO) recording the eruption on Friday shortly before 1 a.m. Universal Coordinated Time, or 8 p.m. Eastern Time (ET) on Thursday.
Solar flares are giant explosions that occur in a localized region of the sun’s atmosphere when energy in “twisted” magnetic fields is released. These events, which tend to arise near sunspots— darker, planet-sized regions on the solar surface—send out into space electromagnetic radiation, such as X-rays, visible light and ultraviolet light, as well as high-speed particles. They can trigger radio blackouts on Earth and solar radiation storms.
Solar flares can be classified according to their strength. The most powerful ones—like the latest event—are known as “X-class” flares, while the weakest are categorized as “A-class.” The latter group is followed by the B, C and M classes in order of increasing strength.
Within each class, solar flares are categorized using an even more detailed scale of strength that runs from 1 to 9. (The exception is X-class flares, which can measure higher than 9.)
Each class represents flares that are at least 10 times more powerful than the previous one. For example, an X-class flare is 10 times stronger than an M-class event, and 100 times more powerful than a C-class flare.
The solar flare recorded on Thursday was rated as “X1.2” on the scale, meaning it ranks among the most powerful flares that the sun produces, albeit at the weaker end of the strongest class.
C-class flares and those smaller are too weak to have any noticeable effect on Earth. M-class flares may trigger brief radio blackouts affecting the polar regions and minor radiation storms if they are directed toward Earth.
X-class flares are the most dangerous events and are capable of triggering radio blackouts across the whole world and long-lasting radiation storms, which can affect satellites, communication systems and even some ground-based technologies, if directed toward us.
The most powerful X-class events are the largest explosions in the solar system by far, capable of producing as much energy as a billion hydrogen bombs, according to NASA.
In the case of the latest solar flare, which was located on the eastern limb, or left side, of the sun, a burst of X-rays and extreme ultraviolet radiation spewed out by the explosion interacted with the Earth’s upper atmosphere, causing a shortwave radio blackout across the South Pacific shortly afterward.
The National Oceanic and Atmospheric Administration’s Space Weather Prediction Center (SWPC) reported that “large portions” of the sunlit side of the Earth—which at the time included the Pacific region—were affected by the radio blackout. Possible effects included widespread signal degradation and loss of contact for up to an hour.
The primary impact was on high-frequency radio communications below 30 MHz, which may have been noticed by ham radio operators, mariners and aviators, SpaceWeather.com reported.
Solar flares are often associated with coronal mass ejections—large expulsions of charged particles with an embedded magnetic field from the outermost part of the sun’s atmosphere (the corona) that can cause geomagnetic storms. But in this case, scientists did not record any CMEs emerging from the area where the solar flare was located.
The sunspot AR3182 had only been visible for less than 24 hours when it produced the X-class solar flare as it emerged from the sun’s far side onto the Earth side.
Just a couple of days before, on Tuesday, the sunspot produced a possible X-class eruption while it was still located on the far side of the sun, an event detected by the SDO and Solar and Heliospheric Observatory (SOHO), a spacecraft jointly operated by NASA and the European Space Agency.
SOHO detected a very bright CME associated with the event, although SWPC scientists predicted that this would narrowly miss Earth in the following days.
The SDO data indicates that the solar flare on Tuesday was “very powerful”—possibly an X-class event—but because it occurred on the far side, much of the radiation was blocked from reaching Earth. This significantly reduced its apparent intensity from our perspective—satellites only detected a C-class event—astronomer Tony Phillips, who operates SpaceWeather.com, wrote in a blog post.
AR3182 poses a significant threat of producing more strong solar flares. Given the size and complexity of this active region, there is a “good chance” that explosions at the site will continue over the coming days, SpaceWeather.com reported.
The number of flares will be expected to increase as we approach the peak of the solar cycle. The sun’s activity is defined by this roughly 11-year-long cycle, which is marked by periods of high and low activity known as solar maximums and minimums.
As the sun approaches a solar maximum, the number of sunspots increases and the effects of space weather on the near-Earth environment tend to be greater. Although sunspots are cooler than the surrounding areas, they contain particularly strong magnetic fields. Most solar flares and CMEs are associated with these regions.
Scientists have recorded 24 complete solar cycles since 1755. We are currently in Solar Cycle 25, which began in 2019 and is predicted to peak in 2025.
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