The sun emitted a moderate solar flare on July 19, 2012, beginning at 1:13 AM EDT and peaking at 1:58 AM. Solar flares are gigantic bursts of radiation that cannot pass through Earth's atmosphere to harm humans on the ground, however, when strong enough, they can disrupt the atmosphere and degrade GPS and communications signals.
The flare is classified as an M7.7 flare. This means it is weaker than the largest flares, which are classified as X-class. M-class flares can cause brief radio communications blackouts at the poles.
Increased numbers of flares are currently quite common, since the sun's standard 11-year activity cycle is ramping up toward solar maximum, which is expected in 2013. It is quite normal for there to be many flares a day during the sun's peak activity.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 184.108.40.206.0