Infrared How different would the world look if we could see infrared, or IR light? Well, for one thing, we would be able to see our hand in front of our face in the dark! Our bodies actually emit IR light, which we experience as heat. The image of the IR man is from the Infrared Processing and Analysis Center at Caltech If we could see in the IR, everything that gives off heat would suddenly be apparent to us, even if there were no visible light! Since our eyes cannot see in the IR, something like night vision (or infrared) goggles can be used to see differences in temperature and to assign different brightnesses or false colors to the different temperatures or energies of IR light. This provides a picture that our eyes can interpret. If we looked at a person with infrared goggles, we would see something similar to the image on the left showing a Jet Propulsion Lab engineer holding a lighted match. The image is color-coded to show differences in temperature. The flame and the engineer's palm (a place where warm blood vessels are close to the surface of the skin) are warmer than his glasses. This shows how infrared images show heat energy and its distribution. X-rays What about X-rays? How do they work? Well, if we could see only X-rays, we could see things that either emit X-rays or halt their transmission. Our eyes would be like the X-ray film used in hospitals. When you get an X-ray taken at the hospital, X-ray sensitive film is put on one side of your body, and X-rays are shot through you. Because your bones are dense and absorb more X-rays then your skin does, dark silhouettes of your bones are left on the X-ray film while your skin appears transparent. When the Sun shines on us at a certain angle, our shadow is projected onto the ground. Similarly, when X-ray light shines on us, it goes through our skin, but allows shadows of our bones to be projected onto and captured by film. To the right is the first X-ray image ever taken. Wilhelm Conrad Roentgen, who discovered X-rays in 1895, took this X-ray of his wife's hand. The shadows of her finger bones and wedding ring are all visible. Previous Next: How does this apply to astronomy? Back to "X-ray Astronomy"

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