The fourth image was taken at radio wavelengths by the Very Large Array. Last, Chandra images x-ray emission from the central region of the Crab Nebula. Each image shows different characteristics of this supernova remnant. Kaleidoscope of Colors In 1666, Isaac Newton took the first step toward understanding visible light when he passed sunlight through a prism and watched it separate into a kaleidoscope of colors. Just like the wavelength differences between various parts of the electromagnetic spectrum, the variety of colors comprising visible light are made of waves that have different lengths between successive crests or troughs.
Red waves are the longest, violet the shortest.
William Herschel, the discoverer of Uranus, was the first to explore the region beyond the rainbow of visible light. In 1800, he reported on experiments to determine the heating power of different colors, in which he let a spectrum of light fall on a set of thermometers. To his surprise, he found that the greatest heat was produced off the red end of the spectrum where nothing was visible. Herschel had discovered infrared radiation. In the mid-19th century, astrophotographers began to explore the other end of the spectrum.