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Plenty of things on Earth can glow, or make their own light. Puerto Mosquito bay, Puerto Rico, is a shining example.
If you run your hand through the water, it sparkles! Millions of very tiny plankton, or microscopic plants and animals, twinkle like stars. Glowing creatures like plankton create light with little heat. But other things glow because they’re hot: coal, charcoal, lava from a volcano. When they’re cold, these things are black and lightless. When they’re hot, they glow a bright reddish orange.
