Part 7/8:
In a twist, the last light source illuminating our planet long after humanity has vanished may stem from an unexpected source: spent nuclear fuel. Contrary to popular belief, radioactivity itself is not inherently luminous. Still, under certain conditions, radioactive particles can emit light, a phenomenon witnessed in glowing nuclear reactor cores.
When radioactive waste, such as cesium-137 (Cs-137), is transformed into glass and stored securely, it emits a distinct blue glow due to a phenomenon known as Cherenkov radiation. This glow remains even as the radioactivity diminishes over the years, giving birth to the notion that these enigmatic glass blocks could serve as a perpetual light source for centuries.