Light consists of any type of electromagnetic radiation. It travels in waves, some of which are visible to the human eye, but most frequencies are not. The visible spectrum of light only covers a narrow portion of the total electromagnetic spectrum: the wavelength of visible light runs from 400 nanometers for violet light to 700 nanometers for red light. The vast portions of the electromagnetic spectrum invisible to the eye have different properties and can potentially be dangerous.
Infrared light radiation exists past the red side of the visible light spectrum; it lies between visible light and microwaves. It can be classified into two portions: near infrared, which is near visible red; and far infrared, which emits thermal energy. According to NASA, false-color images can be used to detect different wavelengths of infrared and in that way develop a relative gauge of temperatures. Hotter temperatures often show up as white or blue, while cooler temperatures show up as red.
Maybe because it's entirely an artist's eye, patience and skill that makes an image and not his tools.
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