The Sun erupted with a large solar flare in the direction of Earth early Friday morning, causing potential disruption to radio signals in the coming days and serving as a prelude to a period of heavy solar activity.

The mid-level flare, classified as an M6.5 solar flare, “was associated with an Earth-direction coronal mass ejection (CME), a solar phenomenon that can send billions of tons of solar particles into space and can reach our planet days later,” according to Science World Report(Opens in a new window). While X-class solar flares are 10 times more powerful than Friday’s eruption, the radiation burst was the largest on record in 2013 and “caused an R2 radio blackout that has since subsided,” the site reported.

The National Oceanic and Atmospheric Administration classifies radio blackouts caused by space weather on a scale from R1 to R5, with R5 being the strongest.

Scientists expect more such solar flares this year, because the Sun’s 11-year activity cycle is approaching its peak, expected to arrive in the closing months of 2013, Science World Report noted.

Friday’s flare occurred at about 3:16 a.m. Eastern while the CME began at 3:36 a.m., “leaving the sun at over 600 miles per second,” according to NASA(Opens in a new window). The space agency published a series of photos of the CME captured by the joint European Space Agency-NASA Solar Heliospheric Observatory (SOHO), below right.

Images captured by the ESA-NASA SOHO satellite show Friday’s solar flare.

When solar flares erupt, they do not always cause CMEs but this one did, slinging one out of the Sun at more than 600 miles per second, according to Science World Report. That has scientists concerned about this particular flare because CMEs can potentially “cause a space weather phenomenon called a geomagnetic storm, which occurs when they connect with the outside of the Earth’s magnetic envelope, the magnetosphere, for an extended period of time,” according to NASA.

If that happens, ground-based and orbiting electronics systems could be disrupted, affecting areas like GPS navigation, satellite communications and broadcasting, air travel, and ground-based radio signaling over cell networks.

“The recent space weather also resulted in a weak solar energetic particle (SEP) event near Earth. These events occur when very fast protons and charged particles from the Sun travel toward Earth, sometimes in the wake of a solar flare. These events are also referred to as solar radiation storms. Any harmful radiation from the event is blocked by the magnetosphere and atmosphere, so cannot reach humans on Earth. Solar radiation storms can, however, disturb the regions through which high-frequency radio communications travel,” NASA said.