Two Solar Flares Friday Continue Week of Intense Solar Activity

The Sun has been feisty this week, emitting a series of solar flares and coronal mass ejections, the effects of which are currently reaching Earth.

NASA reports an X2.1-class solar eruption occurring Friday at 11:03 a.m. EDT, coming just hours after another X-class flare early Friday morning.

According to NASA, an X-class solar flare erupted at 4:01 a.m. EDT. The flare, which measured X1.7, was the second flare in 48 hours, preceded by an M9.4 flare Wednesday night.

X-class solar flares are the most intense type of flare, though Friday's first was relatively weak for an X-class, only slightly more powerful than Wednesday's M9.4.

The numbers following the flare's letter class provide more information about the flare's strength. An X2 flare, for instance, is twice as strong as an X1.

One level below X-class flares, M-class solar flares are the the weakest type of solar flare that can cause some space weather effects near Earth.

Harmful radiation from the solar flares cannot affect humans on the ground, but when intense enough, solar flares can disrupt GPS signals and other satellite data.

Increased numbers of solar flares are common at the moment since the Sun is 11-year activity cycle is near its peak, NASA said.

The first solar flare of the current Sun cycle occurred in February 2011. The strongest flare of the current cycle measured X6.9 on Aug. 9, 2011.

More solar flares are likely to come, according to SpaceWeather.com, which reports a 55 percent chance of another M-class flare and a 10 percent of another X-class in the next 24 hours.

Coronal mass ejections, or CMEs, are related to but different from solar flares, which tend to be localized. CMEs are much larger events, sometimes erupting plumes of radiation larger than the Sun itself.

This week three CMEs were observed leaving the Sun on an Earth-bound course, SpaceWeather.com reported, adding that the trio of CMEs should hit Earth Thursday or Friday. Their combined impact could trigger a mid-polar geomagnetic storm on Earth, which could cause some radio and satellite signals to malfunction, but will more likely just result in some impressive aurora borealis.

"Earth's magnetic field is about to receive a glancing blow from three CMEs observed leaving the Sun between Oct. 20th and 22nd," SpaceWeather reported. "Forecast models suggest that the three clouds merged en route to Earth, and their combined impact could trigger a mild polar geomagnetic storm on Oct. 25. High-latitude sky watchers should be alert for auroras."

The video below is unrelated to this weeks' solar events, but shows shows a coronal mass ejection releasing a long magnetic filament upwards from the surface of the Sun. NASA released the video, taken in September, this week.