(NASA)

Despite being a relatively quiet period for the sun, our star unleashed a powerful solar flare on Tuesday evening that caused a strong radio blackout here on Earth and an audible radio burst.

Tuesday’s flare, which was hurled from sunspot AR2339, was rated X2 on the intensity scale, in which X-class flares are the strongest. “The biggest X-class flares are by far the largest explosions in the solar system and are awesome to watch,” writes NASA. “Loops tens of times the size of Earth leap up off the sun’s surface when the sun’s magnetic fields cross over each other and reconnect. In the biggest events, this reconnection process can produce as much energy as a billion hydrogen bombs.”

Current sunspots. (NASA) Current sunspots. (NASA)

Many solar flares are associated with coronal mass ejections, in which the sun’s gas and magnetic field is carried away by the solar wind. Although it does appear that there was a coronal mass ejection associated with this flare, it is highly unlikely to impact Earth in the form of a geomagnetic storm, given that the flare was pointed away from Earth.

However, the intense flare was strong enough to produce an R3-strong radio blackout over much of the Pacific Ocean and western North America. In R3 blackouts, high-frequency radio communication and low-frequency navigation signals are typically lost for about an hour. “Mariners, aviators, and ham radio operators are the type of people who might have noticed the disturbance,” writes spaceweather.com.

The sun emitted a significant solar flare, peaking at 6:11 pm EDT on May 5, 2015. NASA's Solar Dynamics Observatory, which watches the sun constantly, captured the flare, which was is classified as an X2.7-class flare. Note: This video does not contain audio. (NASA/GSFC/SDO)

According to spaceweather.com, the flare also caused an audible radio burst that was recorded by the shortwave receivers on Pacific islands and western North America. “What caused this burst of ‘solar static’?” spaceweather.com writes. “The same magnetic explosion that caused the flare also produced beams of electrons. As the electrons sliced through the sun’s atmosphere, they generated a ripple of radio-loud plasma waves. Astronomers classify solar radio bursts into five types; this one was a mixture of Type III and Type V.”

Although it has been a quiet period for the sun, it looks like our sun could be turning active again as AR2339 and other sunspots rotate to face Earth.

“We are expecting several active regions to be rotating onto the visible disk later this week and into the weekend,” the Space Weather Prediction Center writes. “We have observed a few, energetic [coronal mass ejections] on the back side of the sun with these regions so we expect that overall solar activity will be on the rise in the short to medium term.”


Locations of radio blackout caused by the X2 solar flare on Tuesday evening. (NOAA)