Why does the Edge SST Mini Cruiser Glow?

Edge SST Penny Style Glowing Green LED

The short version is a phosphorescent phoshor (like Strontium aluminate activated by europium, SrAl2O4:Eu) is capable of storing energy (charged) when expose to light by electrons jumping to higher energy states. When the light is removed, the electrons begin to decay back to a lower energy state by emitting energy in the form of visible light.