On Earth: Superman’s Kryptonite, or is it just Fluorescing? Is Kryptonite real?
Science News Explores
Aaron Tremper
CUM OKOLO/ALAMY
Kryptonite’s out-of-this-world glow is fiction, but Ultra Violet light can give some earthly minerals a glow up!
Superman is faster than a speeding bullet and more powerful than a train. His one weakness? Kryptonite, a radioactive mineral found on the fictional planet Krypton. A power stone that can sap the Man of Steel of his superhuman powers, kryptonite is often shown as a glowing green crystal.
Earth does have its own gleaming green minerals. Some are even radioactive. But these minerals don’t glow on their own like kryptonite. Instead, ultraviolet (UV) light gives these crystals their inner light. There are over 500 kinds of these minerals.
The glow happens because fluorescent minerals contain excitable atoms known as activators. When UV light hits these atoms, their electrons gain energy. The excited electrons jump up to a higher energy state. As they lose energy, they return to their former position. Some energy is lost as invisible heat. The rest is emitted as visible light.
Most of the minerals seen glowing on their own in movies “wouldn’t make much sense,” says Gabriela Farfan. She is the gem and mineral collection curator at the Smithsonian National Museum of Natural History. That’s in Washington, D.C. Fluorescent minerals need a steady energy source to keep them aglow. To keep their shine in a museum, for instance, these crystals are displayed with a UV lamp, says Farfan. Shutting off the lamp stops the glow almost immediately.
