Alice P. Curtin

Somewhere deep in space, a radio beacon flashes for a fraction of a second, and then goes dark. Such signals are called fast radio bursts. They come from other galaxies and last from microseconds to milliseconds.

The night sky looks smooth, but it's actually clumpy — vast communities of galaxies that bend light from distant objects like lenses. When a short, powerful radio burst goes off somewhere in the universe, its path to an Earth telescope can pass near such a clump.

Picture a lighthouse on the shore at night. Its lamp is off almost all the time, but once every few days, for a split second, it blazes so brightly that the light is visible beyond the horizon.