Meet our closest stellar neighbor — Proxima Centauri, sitting just 4.25 light-years from Earth. Sounds close in space terms, and relatively speaking, it is. It was discovered in 1915 and is technically part of the famous Alpha Centauri system, orbiting that pair once every 550,000 years.

It's a red dwarf — only about 14% the size of our Sun and too dim to see without a telescope. But don't let the small size fool you. This star randomly erupts in violent flares, blasting radiation in unpredictable bursts.

Credit: Marco Lorenzi