How powerful solar flares cause radio blackouts on Earth
29 Mar 2025

The Sun has somewhat surprised forecasters by releasing a powerful X-class solar flare from a new sunspot region, AR4046.

It caused radio blackouts in the Americas region.

The intense solar event was preceded by a spectacular filament eruption and coronal mass ejection (CME), which is basically the release of plasma and magnetic field from the Sun.

The CME is unlikely to impact Earth due to the current position of the sunspot region.

Solar physicist comments on CME's trajectory
CME's path

A solar physicist on X with username @halocme, commented on the trajectory of the recent solar event.

He said that "The CME that followed may not be Earth-directed; the region was too close to the east limb."

This indicates that while CMEs can often impact Earth's magnetosphere and trigger geomagnetic storms, this particular one isn't expected to do so due to its current position.

Solar activity under close observation
Monitoring

As AR4046 continues to show solar activity, both space weather forecasters and aurora enthusiasts are keeping a close watch on it.

Solar astrophysicist Ryan French added, "The flare source region will rotate to face Earth in the coming week. Further strong solar activity is likely!"

Once this region rotates to face Earth next week, any CME released then will be more likely to hit our planet and could trigger geomagnetic storms as well as dazzling auroras.

Understanding solar flares and their impact
Solar phenomena

Solar flares are intense bursts of electromagnetic radiation. They are categorized into five classes: A, B, C, M, and X. Each class indicates a tenfold increase in strength.

The latest X-class solar flare was rated X1.1 on this scale.

These powerful solar events can interfere with satellites and trigger radio blackouts when they emit X-rays and extreme ultraviolet radiation into space traveling at light speed to Earth almost immediately.

Radio blackouts and their cause
Communication disruption

The radiation from the solar flare ionizes the upper atmosphere, changing its density. This affects high-frequency shortwave radio signals used for long-distance communication.

As these signals travel through the charged layers of the atmosphere, energy loss from collisions with electrons can weaken or completely absorb transmissions, resulting in radio blackouts.