The death of a star is one of the most dramatic and violent events in space – and astronomers had an unprecedented front-row seat to the explosive end of a stellar giant. Ground-based telescopes provided the first real-time look at the death throes of a red supergiant star. One popular red supergiant star is Betelgeuse, which has captured interest due to its irregular dimming. The star was 10 times more massive than the sun before it exploded. Before they go out in a blaze of glory, some stars experience violent eruptions or release glowing hot layers of gas. Until astronomers witnessed this event, they believed that red supergiants were relatively quiet before exploding into a supernova or collapsing into a dense neutron star. Instead, scientists watched the star self-destruct in dramatic fashion before collapsing in a type II supernova. This star death is the rapid collapse and violent explosion of a massive star after it has burned through the hydrogen, helium and other elements in its core. All that remains is the star's iron, but iron can't fuse so the star will run out of energy. When that happens, the iron collapses and causes the supernova. "Direct detection of pre-supernova activity in a red supergiant star has never been observed before in an ordinary type II supernova. For the first time, we watched a red supergiant star explode," said lead study author Wynn Jacobson-Galán.