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Music

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Rob: Any form of matter that we can think of having a temperature, no matter how hot or cold,

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gives off thermal energy. [ Music ]

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Rob: A chair, a book,

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food, me. [ Music ]

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Rob: Everything around us, even the Earth itself, radiates thermal energy.

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Thermal energy forms the primary source of what we call infrared

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radiation. Infrared being the section of the electromagnetic

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spectrum that is just beyond visible light in terms of wavelength size.

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We cannot see infrared radiation. In fact, humans can

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only see a very small portion of the electromagnetic spectrum, but

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technology allows to detect and image matter in this very important part of the

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spectrum. NASA, NOAA, and other agencies, use thermal

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infrared imagery to study Earth systems in a way beyond what we could ever

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see. Through infrared data, we can study ocean and ice

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changes, map deforestation and forest fires,

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and monitor soil moisture and detect diseased vegetation.

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In fact, nearly every time we look at a weather report, from a heat wave to

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a hurricane, we are using thermal infrared imagery.

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Satellites detect infrared energy in a way that lets us study the Earth's weather patterns

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over both day and night, which is crucial for predicting the weather to come.

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In a way, it's as if the whole planet becomes visible to us at any time

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of day. Just over 200 years ago, Sir William Herschel

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discovered the existence of infrared by studying the sunlight passing through a

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simple prism. The prism separated all the colors that make up sunlight

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in an array called a spectrum. [ Music ]

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Here's a simple classroom activity that lets us see the phenomenon Herschel first observed.

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Herschel measured the temperatures of the different colors

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and found that the temperatures increased as he measured from violet to red.

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But what really struck him was the observation just beyond the visible spectrum.

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First, measure the ambient temperature of the box by placing

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the thermometers in the shade. Once the prism is adjusted for the widest

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spectrum possible, place the thermometers in the blue, yellow,

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and in the area just beyond red. Measuring over time,

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we will see the temperatures increase as we approach this infrared section of the spectrum.

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It may seem like a big jump to go from a prism on a box to

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the advanced imagery satellites provide around the globe, but it all helps