Book 27, Question 117
Why do glow-in-the-dark stars glow?
Glow-in-the-dark materials use special crystals, such as strontium aluminate.
When light hits them, electrons jump to a higher energy and get stuck there for a while. Slowly they fall back and release the energy as a soft glow. The glow lasts minutes to hours, depending on the material. The more light the crystals absorb, the brighter they glow.