Strongest solar storm of the year causes communications and shortwave radio blackouts

7NEWS

15-05-2025

The sun unleashed two huge flares just one day after a NASA observatory captured a dramatic photo of a separate solar flare.
The back-to-back eruptions early on Wednesday US time included the strongest of the year so far and have reportedly caused shortwave radio blackouts on at least five continents.
The outbursts this week may be signalling the sun is ramping up its activity.
Wednesday's solar storm peaked about 4.25am USET, when the sun fired off a huge X-class flare, hurling streams of plasma and charged particles into the cosmos.
'Flares of this magnitude are not frequent,' officials with the National Oceanic and Atmospheric Administration's Space Weather Prediction Centre said.
Solar flares are categorised by strength into five classes. The smallest and weakest flares are A-class storms, followed by B-class, C-class, M-class and the most powerful, X-class. Each letter represents a 10-fold increase in energy released by the sun over the previous class, according to NASA.
In addition to the letters, scientists also use a scale from 1 to 9 to describe the intensity of a solar storm.
During Wednesday's solar tempest, the Space Weather Prediction Centre recorded an X2.7 flare shortly before 4.30am USET, and an M5.3 flare several hours before that.
Dangerous for astronauts
A day earlier, a separate X1.2 flare erupted around 11.38am USET, according to NASA. The agency's Solar Dynamics Observatory, which launched in 2010, snapped a jaw-dropping image of the event, showing the X-class flare as a fiery tendril bursting from the sun.
Strong solar storms can be dangerous for astronauts in space and can cause problems for GPS systems and satellites. When these storms are aimed at Earth, they can also disrupt radio communications or knock out power grids as the planet is bombarded with streams of charged particles.
Since Tuesday, shortwave radio blackouts have been reported in parts of North America, South America, Southeast Asia, Africa and the Middle East, according to Spaceweather.com, a website run by astronomer Tony Phillips that closely monitors the sun's daily activities.
Shawn Dahl, a forecaster at NOAA's Space Weather Prediction Centre, said the X2.7 flare occurred as the sun was over the Middle East, which contributed to disruptions of high-frequency radio signals in the region for about 10 minutes during the storm's peak.
'Other than the likelihood of (high-frequency) communication degradation due to some shortwave fade issues, we are unaware of any other likely or possible impacts,' Dahl said.
But solar storms can also have more innocuous consequences on Earth, such as supercharged displays of the northern lights. As charged particles hit Earth's magnetic field and interact with atoms and molecules in the planet's upper atmosphere, they can intensify auroras at latitudes farther south than normal.
Scientists last year said the sun has entered a busy phase of its natural 11-year cycle. The period of increased activity, known as solar maximum, is likely to continue through this year, which means more solar storms could be in store.
Dahl said while Wednesday's flare was the strongest so far this year, it was not the largest of the sun's current cycle of activity. That designation belongs to a monster flare — an X9.0 eruption — that erupted on October 3, 2024.