The sun emitted two significant solar flares on the morning of Sept. 6, 2017. The first peaked at 5:10 a.m. EDT and the second, larger flare, peaked at 8:02 a.m. EDT. NASA’s Solar Dynamics Observatory, which watches the sun constantly, captured images of both events. 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.