Sun unleashes most powerful solar flare since 2006

Two powerful solar flares erupted from the surface of the sun on Wednesday, disrupting radio communications on Earth's day side. And we might see some other effects in the coming days, mainly in the form of northern lights.

Solar flares occur in cooler regions of the sun, called sunspots. Like Earth, the sun has a magnetic field, sort of like a looped rubber band: at one end is the south pole, the other the north. And as the sun rotates, magnetic loops become wrapped, becoming tighter and tighter as they twist. If they become too entangled, the stored energy is released in the form of a solar flare.

These flares are measured on a scale from one to nine in C, M and X classes, with X being the most powerful. 

On Wednesday, two solar flares erupted from sunspot region 2673: an X9.3 flare followed by a an X2.2 flare. The last such powerful X-class flare was 9.0 on Dec. 5, 2006.

• First NASA craft named after living researcher heads for sun
• NASA's 2 Voyagers explore empty space between stars
• Heads up! Chance to see northern lights on Wednesday night

The flares were powerful enough to cause radio disruptions on the day side of Earth but will continue to disrupt HAM radio communications into the night, space meteorologist Tamitha Skov said in a Periscope Live video.

Solar flares most often produce a secondary effect called a coronal mass ejection, or CME. This is a huge cloud of magnetized particles that travels along the solar wind at incredible speeds, sometimes hundreds of kilometres a second or as fast as thousands of kilometres per second.

If Earth is in the CME's path, the particles interact with our magnetic field. While we're treated to a fantastic light show in the form of the northern lights (which are expected tonight, due to a CME that left the sun on Tuesday), powerful CMEs can cause power grid disruptions. In March 1989, such an event knocked out power to much of Quebec.

While a CME did erupt in the wake of these two solar flares, NASA is still trying to analyze whether or not Earth is in its path.

"Radio emissions suggest a coronal mass ejection (CME) may be associated with the X9.3 flare," they wrote as of Wednesday morning eastern time. "But we await SOHO/LASCO coronagraph imagery for confirmation."

The most powerful event to affect Earth on record is the Carrington Event, named after Richard Carrington, an amateur astronomer who witnessed a solar flare (estimated to be an X10) while sketching sunspots in England in 1859. Less than 12 hours later, northern lights so bright that people were said to have heard birds chirping, were seen; telegraphs failed with some catching fire. 

A 2014 study concluded that Earth narrowly missed a powerful CME in July 2012 that would have rivalled the Carrington Event, in terms of its effects felt, though the flare associated with it was not the strongest recorded.

The most most powerful X-class flare was an incredible X28 (which is the limit of the measuring devices) on Nov. 4, 2003.