On October 18, 2014, a gigantic sunspot on the lower half of the sun rotated into view of NASA’s Solar Dynamics Observatory, or SDO, spacecraft. The sunspot measured 80,000 miles across—big enough to engulf at least a dozen Earths and larger than any seen in more than two decades. With temperatures around 7,000°F, sunspots are relatively cooler areas on the sun. In images taken at visible wavelengths they appear as dark spots on the sun’s surface, hence their name. Over the next 14 days, the massive sunspot unleashed multiple bursts of radiation known as solar flares. Some of these flares were classified as X-class, the strongest type of flare. The mightiest X-class flares (degree is indicated by number, with 1 being the lowest) are by far the largest explosions in the solar system and are awesome to watch. See views of different eruptions captured by SDO in the video.