Sun Fires Off Five Powerful Solar Flares: Could an Aurora or Geomagnetic Storm Follow?

A sunspot region facing Earth produced five M-class solar flares on Aug. 25, including an M6.9 event that peaked at 10:02 UTC, prompting attention from space weather forecasters as a possible CME and a separate high-speed solar wind stream approach Earth later this week.

The Solar Influences Data Analysis Center (SIDC) noted that the flare was accompanied by on-disk solar dimming and that any associated CME would be examined as coronagraph data came in.

The activity came from NOAA active region AR4513, identified by SIDC as its most complex active region on the visible solar disk. The sunspot 4513 was directly facing Earth and that the M-class activity posed a threat of stronger X-class flares, according to SpaceWeather.com.

AR4513 Drives Solar Flare Activity

The largest percentage of flare activity occurred at AR4513, with a total of 16 flares, of which 05 were M-class flares. The worst was an M6.9 (SIDC), with the highest peak at 10:02 UTC.

The event is also reported in space weather as an M7-class flare. The flare caused an R2 moderate radio blackout, and four more M-class flares caused R1 minor radio blackouts in regions such as the Philippine Sea, the Pacific west of Central America, the Philippines, Southeast Asia and the southeast coast of India.

M-class flares are the second-largest category in the classification of solar flares, lower than X-class. The classification is determined by the brightness of the X-rays from a flare.

Earth-Facing Sunspot Could Drive Stronger Storms

AR4513’s position near the center of the Earth-facing solar disk makes it important for space weather monitoring. A CME launched from a region facing Earth has a greater chance of being directed toward the planet than one originating near the Sun’s limb.

An Astronomer’s Telegram report by researchers monitoring the region said, “AR 4513 has been classified as a Beta-Gamma-Delta region.” The report noted that the region had been responsible for renewed solar activity in August, including multiple M-class flares.

SIDC said on Aug. 25 that on-disk dimming was observed around AR4513 in connection with the M6.9 flare, while the corresponding CME still required analysis as coronagraph observations became available.

CME and Solar Wind Stream Could Arrive Together

SIDC said a high-speed solar wind stream associated with positive-polarity coronal hole 159 is expected to begin influencing near-Earth space from late Aug. 27 into early Aug. 28.

SIDC expects geomagnetic conditions to become unsettled to active from Aug. 27, with a chance of reaching minor storm levels as the high-speed stream arrives. Current solar wind conditions remain relatively slow, with speeds of about 330 to 350 kilometers per second in the latest SIDC assessment.

A CME arrival close to the high-speed stream could increase geomagnetic activity, but the resulting conditions cannot be determined solely from the flare’s strength. The CME’s arrival time, speed and magnetic-field orientation will influence how strongly it interacts with Earth’s magnetosphere.

Aurora Outlook and Geomagnetic Storm Risk

SIDC’s latest forecast calls for unsettled to active geomagnetic conditions from Aug. 27, with a possibility of minor storm levels.

A geomagnetic storm classified as G1 is a planet-level storm with a Kp index of 5. These storms may bring auroras closer to the midlatitudes than normal but will depend on the darkness of the sky, cloudiness, latitude, and intensity and duration of the geomagnetic activity.

Geomagnetic activity at minor storm levels would likely result in the greatest aurora activity over northern Europe, northern Canada, and the northern United States.

Sunspot Region Still Threatens Additional M-Class Flares

The elevated activity may not be over. SpaceWeather.com reported that AR4513 remained capable of producing additional M-class flares and posed a threat of stronger X-class eruptions.

Three other numbered active regions were visible on the Earth-facing solar disk. SIDC said the remaining regions were relatively simple compared with AR4513, with AR4517 also producing low levels of flaring activity. Overall, SIDC expected solar flare activity to remain at low to moderate levels, with C-class flares expected and M-class flares likely.

For now, the key dates are Aug. 27 and Aug. 28, when the expected high-speed solar wind stream and the potential CME arrival could overlap. Forecasters will have a clearer picture of the CME’s trajectory and potential geomagnetic impact as additional solar and solar-wind observations become available.