12 Things That Really Glow in the Dark

They range from fireflies to tonic water

The objects, chemicals, and products listed here are all known to emit light via phosphorescence. They are some of the most famous things that glow in the dark.


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Fireflies glow to attract mates and also to encourage predators to associate their light with a nasty-tasting meal. The glow is caused by the chemical reaction between luciferin, a compound produced in the tail of the insect, and oxygen from the air.


Blue Radium
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Radium is a radioactive element that emits a pale blue color as it decays. However, it is best known for its use in self-luminous paints, which tend to be green. The radium itself doesn't emit green light, but the decay of the radium provides the energy to light the phosphor used in the paint.


Plutonium pellet glowing by its own radioactivity.
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Not all radioactive elements glow, but plutonium does. The element reacts with oxygen in the air, causing it to glow a deep red, like a burning ember. Plutonium doesn't glow because of the radiation it gives off, but because the metal essentially burns in the air. It's called being pyrophoric.


Glow sticks are a glow party staple. You can wear them, hang them, swing them, and wrap them around glasses.

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Glowsticks or lightsticks emit light as the result of a chemical reaction or chemiluminescence. Generally, this is a two-part reaction in which energy is evolved and then used to excite a colored fluorescent dye.


Moon jellyfish
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Jellyfish and related species often exhibit bioluminescence. Also, some species contain fluorescent proteins, causing them to glow when exposed to ultraviolet light.

Fox Fire

This fungus is displaying the type of bioluminescence known as foxfire.

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Fox fire is a type of bioluminescence exhibited by some fungi. Fox fire most often glows green, but a rare red light occurs in some species.


Phosphorus glows because of a chemical reaction with oxygen.
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Phosphorus, like plutonium, glows because it is reacting with oxygen in the air. Phosphors and phosphorus glow an eerie green. Although the element glows, phosphorus is not radioactive.

Tonic Water

The quinine in tonic water fluoresces bright blue.
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Both regular and diet tonic water contain a chemical called quinine, which glows bright blue when exposed to black or ultraviolet light.

Glowing Paper

Bleaching agents in paper cause it to glow under invisible light.
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Whitening agents are added to bleached paper to make it appear brighter. While you don't ordinarily see the whiteners, they cause white paper to appear blue under ultraviolet light.

Some papers are marked with fluorescent dyes that appear only under certain lighting. Bank notes are a good example. Try looking at one under a fluorescent light or a black light to reveal additional information.


The tritium sights of this handgun glow in the dark.
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Tritium is an isotope of the element hydrogen that emits a greenish light. You'll find tritium in some self-luminous paints and gun sights.


Radon glows red when it's cooled.
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Radon is a colorless gas at room temperatures, but it becomes phosphorescent as it is cooled. Radon glows yellow at its freezing point, deepening toward orange-red as the temperature is lowered even further.

Fluorescent Coral

Many types of coral are fluorescent.

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Coral is a type of animal related to jellyfish. Like jellyfish, many forms of coral either glow on their own or when exposed to ultraviolet light. Green is the most common glow-in-the-dark color, but red, orange, and other colors are also known to occur.