NASA / LMSAL via SpaceWeather. com This color-coded image
combines observations made by NASA's Solar Dynamics Observatory
in several extreme ultraviolet wavelengths, highlighting a
bright X-class flare toward the upper left of the sun's disk on
March 6. The sun unleashed one of the biggest flares ever seen
during its current activity cycle late Tuesday — an X5.4-class
outburst strong enough to trigger a radio blackout. The
resulting geomagnetic storm could affect electrical grids,
communication links, satellite navigation systems and airline
schedules over the next couple of days. The outburst at 7:24
p.m. ET was followed about an hour later by an X1.3-class blast.
Solar flares are rated on a letter-plus-number scale, with X
being the most powerful category. Usually the numbers run from 1
to 9, but X-class flares can run higher. The highest reading
recorded recently is an X28, observed in 2003. Joe Kunches, a
space scientist with the National Oceanic and Atmospheric
Administration's Space Weather Prediction C