The Sun just released the most powerful solar flare this cycle. Expect more

On Thursday a massive solar flare erupted from the Sun – causing a moderate radio blackout in South America and producing spectacular auroras for the last few days.

But, although this is the most powerful solar flare recorded in six years, experts say this could just be the tip of the iceberg, as the Sun ramps up for the solar maximum around July 2025.

“This was the largest solar flare that has occurred since 2017,” Dr Kate Brand, Australian Space Weather Forecasting Centre manager for the Bureau of Meteorology, told Cosmos.

“As we approach solar maximum it is likely that we will see more frequent, and potentially more intense solar flares.”

The flare on Thursday was caused by an active sunspot region named AR 3514. The flare was recorded as a class X2.8 solar flare. The ‘X’ means it’s the most intense of 5 categories, with the number noting its intensity within that. It was also classed as an R3 event.

“The R-scale is a measure of solar flare activity, which can cause radio blackouts,” said Brand. “The R-scale ranges from R1 (minor) to R5 (extreme).”

While the flare was spectacular (you can see a gif below), it’s not the only event. Solar flares are bursts of electromagnetic radiation and reach the Earth quickly. Coronal mass ejections (CME) are slower, but release both magnetic field and plasma. These CMEs can take days to reach the Earth.

“Solar flares can cause radio blackouts, affecting radio communications, GPS navigation and radar technology,” said Brand.

“During a coronal mass ejection, billions of tonnes of magnetised solar plasma erupt into space at speeds up to 3,000 km/s. If the material is directed towards the Earth, geomagnetic and ionospheric storms can occur. Both can significantly disrupt technology in the near-Earth space environment.

“Solar flares do not cause coronal mass ejections, but a coronal mass ejection may (or may not be) associated with a solar flare.”

Luckily in this case the flare was not directed at Earth, but created a glancing blow. This is important, because flares and coronal mass ejections that hit Earth head on can cause significantly more issues.

“A US-owned satellite in geostationary orbit, GOES, detects the increase in X-ray levels near Earth from a solar flare only if the region that the solar flare came from is facing Earth,” says Brand.

“In addition, the resultant impacts to technology (termed a ‘radio blackout’) only affect the dayside of Earth (the side facing the Sun).”

The flare also means we’re likely to see more auroras this week, including in latitudes further away from the poles.

“A CME arrival earlier on 17 December is likely to bring some further minor enhancement to the auroral oval,” the UK Met Office writes on their website.  

“This may bring visible aurora to Scotland, Northern Ireland, northern England and similar geomagnetic latitudes. A second smaller peak in activity is then possible on 19 into 20 December, with a more limited reach.”

The Sun is ramping up as part of its 11-year cycle. We’re currently nearing the peak of this cycle – called the solar maximum – but depending on who you ask, this could occur anywhere in 2024-25, and we won’t know until after it happens.

As we get towards that peak, groups like Brand’s will be busy making sure we’re prepared.

“In the Australian Space Weather Forecasting Centre, (ASWFC) Bureau of Meteorology, we are constantly monitoring the Sun through space and Earth-based observations,” she says

“There are numerous satellites (and ground-based telescopes) pointed at the Sun, enabling us to see and analyse the events within the ASWFC. We then issue relevant forecasts, warnings and alerts are issued to inform owners and operators of critical infrastructure and technology that may be impacted by space weather, to ensure that they are able to take any mitigating actions to minimise impacts.”