A NASA spacecraft captures stunning views of a solar flare.
On April 17, 2016, the sun emitted a huge burst of radiation known as a solar flare. The flare appeared as a bright flash of light in images taken by NASA’s Solar Dynamics Observatory, or SDO, spacecraft, which watches the sun constantly. 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. This particular flare was of moderate strength and only caused brief radio blackouts. It came from a large dark spot on the sun, called a sunspot. These dynamic regions can grow to many times the size of planets and have complex magnetic activity that lead to solar eruptions. Watch the video for a look at the solar flare, as seen by SDO.