An M-class flare erupted in active sunspot region 1093, peaking at 1824 UTC on August 7, 2010. The eruption hurled a coronal mass ejection (CME) into space. NASA's Solar Dynamics Observatory observed the flare. The CME is not fully directed toward Earth, but some of the plasma cloud may glance the magnetosphere between August 9 and August 10, causing a geomagnetic disturbance and possible aurora.
Scientists classify solar flares according to their x-ray brightness in the wavelength range 1 to 8 Angstroms. There are 3 categories: X-class flares are major events that can trigger planet-wide radio blackouts and long-lasting radiation storms. M-class flares are medium-sized; they can cause brief radio blackouts that affect Earth's polar regions. Minor radiation storms sometimes follow M-class flares. Compared to X- and M-class, C-class flares are small with few noticeable consequences on Earth.
For more information visit http://www.nasa.gov/topics/solarsystem/sunearthsystem/main/News080910-flare.html