An active region at the Sun's edge produced several M5-class (medium sized) flares over a ten-hour period (April 3, 2017). These were the strongest flares of the year so far. Some coronal mass ejections (which hurled clouds of plasma into space) were also associated with some of these flares. The images were taken in a wavelength of extreme ultraviolet light.
Image Credit: NASA/GSFC/Solar Dynamics Observatory
Explanation from: https://photojournal.jpl.nasa.gov/catalog/PIA21584