In fiction, some superheroes have special vision. In WandaVision, for instance, Monica Rambeau can see energy pulsing from objects all around her. And Superman has X-ray vision and can see through objects. These are definitely super talents, but it’s not that different from what normal humans can do. That’s because we can see also see a type of energy: visible light.
Light’s more formal name is electromagnetic radiation. This type of energy travels as waves, at a constant speed of 300,000,000 meters (186,000 miles) per second in a vacuum. Light can come in many different forms, all determined by its wavelength. This is the distance between the peak of one wave and the peak of another.
The light we can see is called visible light (because we can, er, see it). Longer wavelengths appear as red. Shorter wavelengths look violet. The wavelengths in between fill in all the colors of the rainbow.
But visible light is only a small part of the electromagnetic spectrum. Longer wavelengths just past red are known as infrared light. We can’t see infrared, but we can feel it as heat. Beyond that are microwaves and radio waves. Wavelengths a bit shorter than violet are known as ultraviolet light. Most people can’t see ultraviolet, but animals such as frogs and salamanders can. Even shorter than ultraviolet light is the X-ray radiation used to image inside the body. And still shorter are gamma rays.
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