NASA has captured images of the largest and most intense solar flare seen in years, one of three powerful eruptions from the sun that were observed in a span of 24 hours, temporarily knocking out shortwave radio communications on Earth.
The first two — rated X1.7 and X1.8 in magnitude — occurred Wednesday night and early Thursday. The last and most explosive flare late Thursday afternoon clocked in at a rating of X6.37 in flare intensity, according to NOAA’s Space Weather Prediction Center.
Similar to hurricanes and earthquakes, solar flares are rated according to their intensity. The “X” denotes the most intense flares and the higher the number, the more powerful an eruption from the sun’s surface.
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“Flares of this magnitude are not frequent,” NASA officials said in a posting about the eruption.
Thursday evening (Feb 22nd) large sunspot group, 3590 produced the largest flare of current solar cycle - an X6.3 (R3) event as seen in this blend of NASA SDO imagery showing the spot group and the flare. credit: https://t.co/OaQyap5MwP - part of the ESA-NASA Helioviewer Project pic.twitter.com/4IuM9fRcZ5
— NOAA Space Weather (@NWSSWPC) February 23, 2024
“Yesterday’s X6 flare was the largest in the current solar cycle and was also the largest since 2017, since larger flares occurred near the peak of the previous solar cycle,” said Dr. Ryan French, a solar astrophysicist at the National Science Foundation’s National Solar Observatory in New Mexico, in an interview Friday. “We are certainly entering an increased period of solar activity!”
In fact, this X6.3 burst of radiation was more powerful than the solar flare NASA measured on Dec. 18.
The sun typically follows an 11-year solar cycle, with increasing numbers of flares and sunspots erupting until it reaches its peak mid-cycle. The current Solar Cycle 25 started in 2020 and is expected to “reach peak activity” this year, French said.
Robert Leamon, associate research scientist at the NASA Goddard Space Flight Center, said this most recent active period of solar flares “will last for another few days and then there will be a recharge period (for the sun), which will last for a couple of months.”
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What are solar flares?
A solar flare, the solar system’s largest explosive event, is an intense burst of radiation coming from the release of magnetic energy associated with sunspots.
The flares hurl X-rays out into the solar system and can affect radio propagation in the upper atmosphere, arriving at Earth with the speed of light. But harmful radiation from a flare cannot pass through Earth’s atmosphere to physically affect humans on the ground. This latest trio of solar flares erupted from the same AR13590 region of the sun, according to NASA.
Such flares can also spark geomagnetic storms on Earth, when charged particles affect the upper atmosphere. The captivating aurora borealis or “Northern Lights” occur during these storms.
NASA released several images of the two initial flares, including one showing the immensity of a flare compared to Earth:
Another look at one of last night’s X-class solar flares, with Earth added for a size reference.
— NASA Sun & Space (@NASASun) February 22, 2024
Wow! 🤩
This amazing view of the Sun courtesy of NASA’s Solar Dynamics Observatory. pic.twitter.com/Z0bsEBhPui
Can solar flares and CMEs cause cellphone outages?
What’s more concerning, scientists said, is when a solar flare produces a “coronal mass ejection” or CME – an explosive event that is more likely to threaten communication technology on a large scale. A CME occurs when there is a large eruption of plasma from the sun.
Also unlike flares, CMEs travel at a few hundred miles per second and take several days to reach the Earth.
But French and other scientists quickly dispelled any connection between the recent initial solar flares and Thursday’s cellular network outage that followed, impacting emergency communications in Massachusetts. Many people circulating theories on social media had pointed to solar flares as the cause.
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“The worst impacts of space weather, including potential damage to power grids, potential physical damage to cell towers, satellites, and other technological infrastructure, come from an impact of a CME with Earth, not from the initial flare,” French said, explaining that none of the recent flares produced “any large eruption.”
NOAA said these recent flares were rated R3 on a 1 through 5 scale in terms of radio blackouts, meaning they were strong enough to knock out high-frequency or shortwave radio communication for about an hour on the sunlit side of Earth, but not cellular networks.
“Users of high frequency radio signals may experience temporary degradation or complete loss of signal on much of the sunlit side of Earth. The general public need not be concerned,” NOAA said in reporting the flares Thursday morning.
Shortwave communications operate on a frequency of 3 to 30 megahertz (MHz) while most cellphones operate on a 700 MHz to 2000 MHz frequency range.
When CMEs do happen, there can be widespread impacts on our planet. Explosive CMEs have caused significant communications and infrastructure damage in recent history: In March 1989, a powerful coronal mass ejection the size of roughly 30 Earths hit the planet’s magnetic field, triggering a nine-hour blackout that affected 6 million people. And in February 2022, about 40 Space X satellites failed to reach orbit because of a strong CME event.
Globe correspondent Chris Gloninger contributed to this report.
Marianne Mizera can be reached at marianne.mizera@globe.com. Follow her @MareMizera.