Our closest neighbor star is a bare cosmic ember. It’s much lighter and smaller than the Sun, and less than one ten-thousandth as bright. Yet the star produces giant explosions that are much more powerful than anything ever seen from the Sun. An outburst two years ago, in fact, was the brightest from any star at some wavelengths.
Proxima Centauri is just four-and-quarter light-years away, but it’s too faint to see without a telescope.
The star is put together a little differently from the Sun. A conveyor-belt effect carries hot gas from the core to the surface, where it cools and falls back toward the core. This motion generates a powerful magnetic field. As the star spins, the lines of magnetic force get tangled. When they cross, they snap, producing massive eruptions.
Proxima has produced many such outbursts over the years. But one in May of 2019 beat them all. Astronomers recorded a flare that lasted just seven seconds. At visible wavelengths, though, it was a hundred times brighter than any flare seen from the Sun. And it was even brighter in X-rays and ultraviolet light — the brightest ever seen from any star.
Two planets orbit Proxima Centauri. One of them is at a comfortable distance from the star for life. But getting zapped by such powerful radiation is dangerous. So if anything lives on the planet, it most likely would have to be quite different from life on Earth to survive such powerful outbursts.