What is Infrared?

What is Infrared?

Infrared light is a kind or form of light. Light that we cannot see with our eyes but may occasionally feel as heat on our skin.

When we think about light, we may conjure up images of the brilliance of the Sun on a hot day or the warm glow of a light bulb at night. However, visible light, the only light our eyes can see, accounts for only a minuscule fraction of all the light in the world around us.

Infrared light exists just outside the visible spectrum, beyond what humans see as red. Sir William Herschel discovered infrared light in 1800.By pouring sunlight through a prism, he divided light into a rainbow (called a spectrum), and then put thermometers in different hues within that spectrum. Surprisingly, the thermometer exhibited an increase in temperature even when put in the dark region beyond the red light's edge. He reasoned that there must be more light than the hue red that we couldn't perceive with our own eyes. You may conduct Herschel's experiment with a box, a prism, three thermometers, and a few other ordinary household items.

Light does not cease at visible and infrared wavelengths. You may have heard of gamma rays, X-rays, UV light, microwaves, and radio waves. Everything in this spectrum moves at the Universe's ultimate speed limit, which is, of course, the speed of light.

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The Electromagnetic Spectrum

Light moves through the Universe as a wave, yet it is not like the ripples we perceive on the surface of a lake. Electric and magnetic fields combine to form light waves. Light is also known as electromagnetic radiation. The electromagnetic spectrum refers to the complete spectrum of light.

The wavelength of a wave is one of its fundamental qualities; it is just the distance between the peaks of one ripple or wave and the next. It is the length of one whole cycle, or pulse, of the electric and magnetic fields for light. The frequency, or the number of waves that pass a specific place per second, is a related parameter.

Changes in the wavelength of visible light are detected by our eyes as differences in color. Color is essentially your brain's technique of swiftly turning the many wavelengths of light that your eyes sense into something that you can understand. The wavelength of red light is longer than that of green light, which in turn has a longer wavelength than that of blue light. Infrared light has a far longer wavelength than red light, in some instances hundreds of times longer. These longer wavelengths carry less energy than red light and do not activate our eyes' photoreceptors, therefore we cannot see them.

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Heat and Light

Is there a link between heat and light because we conceive of infrared light as something that makes us feel warm? Is it the same thing?

The true link is that everything in the Universe that is heated emits light. This applies to stars, planets, humans, and even the Universe! This type of light is referred to as blackbody radiation by physicists. This light is emitted by every item in the Universe, even those as dark as a lump of charcoal. The location of this light in the spectrum, however, is determined by the temperature of the item.

Cooler items shine weakly at longer light wavelengths, whereas hotter ones glow strongly at shorter wavelengths. Our Sun's temperature is a scorching 5,778 K (9,940° F), making it glow brightest at visible wavelengths of light (around 0.4 - 0.7 microns). People who are significantly colder (310 K, 98° F) glow, but in infrared light with a wavelength of roughly 10 microns. 1 millionth of a meter is one micron.

The Cool Cosmos

In order to investigate the coldest things in the Universe, astronomers use infrared telescopes to show their faint light. Dust clouds with temperatures ranging from hundreds to tens of degrees above absolute zero look as black soot in visible sight but shine brilliantly at infrared wavelengths reaching several hundred microns.

In order to investigate the cold universe, we need a window into the heat of the coolest objects on the planet.