A. Razumov

Deep in the Siberian taiga, there are a hundred light traps: each about the size of a small table, but together they cover a square kilometer. At night, these traps gaze at the sky, catching faint flashes of light born when cosmic particles slam into the atmosphere. The setup is called TAIGA-HiSCORE, and it usually works as a giant "eye" for such particles.

At night over the Siberian taiga, a faint blue light sometimes flickers. It's not the aurora borealis but a cosmic-ray shower: a single particle from deep space slams into the atmosphere and shatters into millions of secondary particles. They race toward the ground in a broad front, like a ripple from a stone dropped into water, and make the air glow.