I assume you're thinking of N-Rays and Blondlot, but there is another phenomenon that more or less fits your description. https://en.wikipedia.org/wiki/Cosmic_

I assume you're thinking of N-Rays and Blondlot, but there is another phenomenon that more or less fits your description. https://en.wikipedia.org/wiki/Cosmic_ray_visual_phenomena https://en.wikipedia.org/wiki/Cosmic_ray_visual_phenomena It's interesting that according to the Wikipedia article it's not entirely certain whether the radiation is producing actual light or just the sensation of light.