May 13, 2013
Sun Produces An X1.7 Solar Flare, Followed By An X2.8
Lawrence LeBlond for redOrbit.com - Your Universe Online
On Sunday (May 12) the Sun emitted a significant solar flare that is being classified as the first X-class event of 2013. The X1.7 flare, which peaked at about 10 p.m. EDT, was also associated with another solar event known as a coronal mass ejection (CME). While CMEs can release radiation and solar material in the direction they were produced, Sunday´s phenomenon was not directed at Earth.While solar flares also have the potential to release bursts of radiation, they do not pose a threat to humans on Earth. Harmful radiation from flares, such as Sunday´s event, can only affect GPS systems and communication signals that travel in the upper atmosphere. This can disrupt radio signals for as long as the flare occurs.
The “X” denotes the intensity level of the flare, with X-class events being the most intense, much more intense than M-class flares. The number that follows the X provides information on the strength of the flare as well — an X2 flare is twice as intense as and X1 and an X3 is three times as intense.
Sunday´s flare erupted from an active region just out of sight over the left side of the sun. This same region has produced two smaller M-class flares as well. The CME that was associated with Sunday´s flare left the sun at 745 miles per second. NASA said in a statement that while the CME was not Earth-directed it could flank the STEREO-B and Spitzer spacecraft. There is some particle radiation associated with this event, so the space agency said it had alerted the spacecraft operators to put onboard electrical systems on standby to protect them from damaging effects of the radiation.
While Sunday´s impressive X1.7 solar flare was the first X-class flare of 2013, it was not the only one to occur. NASA's Solar Dynamics Observatory (SDO) reported today on Facebook that a second X-class solar flare occurred within 24 hours of the first. This event was even bigger than the first and is classified as an X2.8 flare. This event was also not Earth-directed.
An increased number of flares are relatively common as the Sun's 11-year activity cycle is building toward solar maximum, which is expected to peak this year. The solar cycle has been tracked continuously since it was first discovered in 1843.
Experts said it is normal for so many flares to pop up during this peak time of the cycle. There have been at least a dozen X-class flares since the first one of the current cycle was detected on February 15, 2011. The largest X-class flare in this cycle occurred on August 9, 2011 and was classified as an X6.9.