The sun emitted a mid-level solar flare, peaking at 6:34 p.m. EDT on March 12, 2014, and NASA's Solar Dynamics Observatory, or SDO, captured an image of it. Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however--when intense enough--they can disturb the atmosphere in the layer where GPS and communications signals travel.