The sun emitted a trio of mid-level solar flares on April 2-3, 2017. The first peaked at 4:02 a.m. EDT on April 2, the second peaked at 4:33 p.m. EDT on April 2, and the third peaked at 10:29 a.m. EDT on April 3. NASA’s Solar Dynamics Observatory, which watches the sun constantly, captured images of the three 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.