In 2021, astronomers discovered a massive cosmic event that outshone everything in its galaxy—a colossal explosion known as AT2021lwx. This extraordinary event, 100 times brighter than a typical supernova, is the most luminous explosion ever recorded. To put it into perspective, it’s like comparing a firework to a nuclear bomb in terms of brightness and energy. AT2021lwx stretched across space, with a fireball 100 times the size of our solar system, releasing more energy than the Sun will in its entire 10-billion-year lifetime.
This monumental explosion was first spotted by the Zwicky Transient Facility, a state-of-the-art telescope at Palomar Observatory in California. The facility is designed to scan the skies every night, searching for any cosmic events, such as new stars or supernovae. On one of these nights, ZTF detected an incredibly bright flash of light. At first, astronomers weren’t sure what they were looking at, but it quickly became clear that this event was truly extraordinary.
AT2021lwx was brighter than any supernova, a type of star explosion that typically occurs at the end of a star’s life. The initial assumption was that it was a superluminous supernova, which are already about ten times brighter than regular supernovae. However, further research suggested that the only possible explanation for the sheer power of AT2021lwx could be the interaction of a supermassive black hole or a tidal disruption event, where a black hole tears apart a star and creates a bright flare. Another possibility is that AT2021lwx could be similar to a quasar, where a supermassive black hole swallows a massive cloud of gas.
At its peak, AT2021lwx shone with a luminosity about 2 trillion times brighter than the Sun. The energy released over several months was more than the Sun will emit in 10 billion years. This prolonged brightness helped astronomers understand that they were witnessing something unprecedented. The explosion’s vast scale would have been visible even during the day if it were closer to Earth.
While the brightness of AT2021lwx was staggering, the intense radiation it released would have been catastrophic for any nearby planets, potentially stripping away their atmospheres and making life impossible. If this explosion had occurred within 10 light years of Earth, the gamma rays and x-rays it emitted could have triggered a mass extinction.
Studying events like AT2021lwx gives scientists a chance to learn more about the universe. It helps test theories on stellar explosions, black hole interactions, and the behavior of matter in extreme gravitational fields. These rare cosmic events also provide insight into how galaxies evolve and how black holes grow, pushing the boundaries of what we know about the cosmos.
