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.
Want to know more? We’ve got some stories to get you started:
Understanding light and other forms of energy on the move: Radiation doesn’t need to be scary, especially if it allows us to see our family or use our cell phones. Here’s a guide to light and other types of emitted energy. (7/16/2020) Readability: 6.7
Ancient light may point to where the cosmos’ missing matter hides: The universe is missing some of its matter. Now astronomers may have a way to find it. (11/27/2017) Readability: 7.4
Explainer: How our eyes make sense of light: It takes a lot for images before the eyes to be ‘seen.’ It starts by special cells sensing the light, then signals relaying those data to the brain. (6/16/2020) Readability: 6.0
Light bends when it encounters an object — something called refraction. You can use that bending to measure the width of a single hair. All you need is a dark room, a laser pointer, some cardboard, tape — and of course, some hair.