Flare from a star known as EV Lacertae. This flare was thousands of times more powerful than the greatest observed solar flare. Rated Top One Hundred Ranked File of Mattes out of 24,516,222 Wikimedia Commons files.
Transition Region and Coronal Explorer (NASA), ...more...
Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion 325 years ago.
Twenty years ago, astronomers witnessed one of the brightest stellar explosions in more than 400 years. The titanic supernova, called SN 1987A, blazed with the power of 100 million suns for several months following its discovery on Feb. 23, 1987. Observations of SN 1987A, made over the past 20 years by NASA’s Hubble Space Telescope and many other major ground- and space-based telescopes, have significantly changed astronomers' views of how massive stars end their lives. Astronomers credit Hubble's sharp vision with yielding important clues about the massive star's demise. This Hubble telescope image shows the supernova’s triple-ring system, including the bright spots along the inner ring of gas surrounding the exploded star. A shock wave of material unleashed by the stellar blast is slamming into regions along the inner ring, heating them up, and causing them to glow. The ring, about a light-year across, was probably shed by the star about 20,000 years before it exploded.