Probing the first stars and galaxies: Herschel's Science Goals
What is infrared light?
Infrared light is a type of light that is not visible to the naked eye. It is very useful to astronomers because it gives them precious information on the amount of heat produced by an object. That means that scientists have access to information that would otherwise be hidden. For example, if you look at the following infrared images of the dog and caterpillar, you can see that the dog is a warm-blooded animal (warm colours indicate heat) while the cold-blooded caterpillar is blue next to the warm hand of the person holding it.
Thanks to infrared light, astronomers can investigate stars, galaxies, and other celestial bodies by peaking through dust clouds and other molecules, which would otherwise obstruct their vision. The pictures shown above show the same image seen in visible light (left) and in infrared light (right). The hand of the person is hidden in visible light, but it is revealed with the infrared light.
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