A massive stellar flare from Proxima Centauri, the closest star to our solar system, might have incinerated any hope that Proxima b, the star’s exoplanet, could support alien life.

In August 2016, astronomers announced the discovery of Proxima b, a rocky planet orbiting Proxima Centauri some 4.24 light-years from Earth. The exoplanet soon became a top candidate in the search for alien life because of its similarity to Earth: it's rocky, has a similar mass, and has temperatures that could support liquid water.

But unlike Earth, Proxima b orbits a red dwarf, a class of dim stars prone to cataclysmic flares that are powerful enough to destroy atmospheres. Proxima b is also much closer to Proxima Centauri than Earth is to the Sun, meaning that a stellar flare would hit the exoplanet with 4,000 times more radiation than we typically receive from the Sun’s flares.