Things That Glow in the Dark 1

Here’s a handy list of things that glow in the dark. I’m talking about objects and substances that truly emit light and glow on their own. This is different from a list of things that glow under black light, which are fluorescent and phosphorescent, not truly luminescent. Really glowing includes light produced by the following processes:

Things That Glow From Chemiluminescence

Chemiluminescence is light produced by chemical reactions. Typically, this is a two-part reaction where the first reaction releases energy that causes a fluorescent molecule to glow. Here are some examples:

• glow sticks – these rely on the cyalume chemical reaction
• luminol reaction – chemical reaction used in chemistry demonstrations and to detect blood that glows bright blue

Things That Glow From Bioluminescence

Bioluminescence is a special form of chemiluminescence produced by living organisms. Examples include:

• firefly light – reaction between luciferin in the firefly and oxygen in air
• glowing jellyfish – other forms of marine life also often glow, including many species of coral
• foxfire – a type of bioluminescence seen in glowing fungi
• dinoflagellates

Things That Glow From Incandescence

Incandescence is light produced by heat. Classic examples include:

• hot burners or other metal – glow infrared, red, orange, yellow, and white hot
• light from the sun – of course, the sun also releases light from fusion and other processes
• incandescent light bulb – contains a metal filament that glows when heated

Glowing from Triboluminescence

Triboluminescence occurs when mechanical stress breaks the chemical bonds in crystals, releasing light. Several materials emit light when crushed, including:

• wintergreen candies (e.g., Wint-O-Green Lifesavers)
• snow
• quartz

Glowing Radioactive Materials

Most radioactive materials do not glow. Those that do emit light usually glow from heat (incandescence), because they oxidize or burn in air, or because they release energy which is then used to illuminate a phosphor. These radioactive materials glow:

• tritium – radioactive isotope of hydrogen, commonly seen in gun sights and watches
• radon – the color this element glows depends on its temperature. It’s phosphorescent yellow near its freezing point, becoming red as it is chilled even further.
• radium – glows green because of the phosphor that is used to release light
• actinium
• plutonium – glows red because it’s pyrophoric, which means the surface burns in air
• Cherenkov radiation – blue light associated with nuclear reactions

Phosphorescence to Make Things Glow in the Dark

Most of the materials people think of as “glow in the dark” are phosphorescent, which means they absorb light and then slowly release part of the absorbed energy as visible light. Many phosphorescent materials don’t glow very well on their own, but are bright when they are exposed to an energetic light source, such as a black light. Other phosphorescent materials glow for several hours. It’s interesting to note the element phosphorus, which glows, is not phosphorescent. Phosphorus glows in the dark as it oxidizes or reacts with oxygen in the air. Phosphorescent materials include:

• zinc sulfide – found in glow in the dark stars and many other products, usually glowing green
• alkaline earth metal aluminates – for example, strontium aluminate doped with europium. These are the brightest and longest-lasting glow in the dark pigments at present.