Sun unleashes powerful X-class solar flare, knocking out radio signals across Australia

close up view of the sun emitting the giant solar flare in a fiery eruption — A powerful X1.9 solar flare from new sunspot AR4299 triggered strong radio blackouts, as giant sunspot AR4294 rotates into view with more activity likely. (Image credit: NASA / SDO and the AIA, EVE, and HMI science teams / helioviewer.org)

The sun kicked off December with a bang, unleashing a strong X1.9-class solar flare that briefly knocked out radio communications across Australia and parts of southeast Asia.

map showing strong radio blackouts across australia shortly after the x-flare eruption. — The X-1.9 solar flare sparked radio blackouts across Australia. (Image credit: NOAA Space Weather Prediction Center)

Coronagraph imagery from SOHO revealed a rapid partial-halo coronal mass ejection (CME), a release of plasma and magnetic field from the sun, blasting off the sun's northeast limb. Earth modelling confirms that the CME is not Earth-directed.

But the real story might be in the enormous sunspot region following closely behind this flare. AR4294, a sprawling, magnetically complex sunspot cluster, is now turning toward Earth. It is so complex that NOAA has split the region into three numbered groups because of its size and complexity. This is also the same area of the sun responsible for multiple X-class flares last month — and it's only grown even larger.

a detailed bulletin from NOAA reiterating what to expect this week from the large sunspot region rotating into view. — NOAA's Space Weather bulletin for the week of Dec. 1-5, 2025. (Image credit: NOAA Space Weather Prediction Center)

NOAA space weather forecasters anticipate a likely continuation of M-class solar flares and a slight chance of more X-flares between Dec. 1-3. While no Earth-directed CMEs have been detected, increased activity from AR4294 could change that in the days ahead, so watch this space!

Meanwhile, geomagnetic conditions are expected to stay mostly quiet until Dec. 3, when a negative-polarity coronal hole stream may bring minor (G1) geomagnetic storming.

Daisy Dobrijevic joined Space.com in February 2022, having previously worked as a staff writer for All About Space magazine. She completed an editorial internship with BBC Sky at Night Magazine and worked at the National Space Centre, communicating space science to the public.

Daisy holds a PhD in plant physiology and a Master's in Environmental Science. Based in Nottingham, U.K., she covers all things space, with a special focus on solar activity and space weather. She also has a keen interest in astrotourism and is always on the lookout for the next northern lights adventure.

She will be a guest speaker aboard HX's Solar Eclipse Expedition in August 2026 and will join Hurtigruten as an onboard astronomer for a northern lights sailing in January 2027.