Color reflected color depends upon the viewing angle. Numerous scientists have carried out research in butterfly wings and beetle shells, including Isaac Newton and Robert Hooke. Since 1942, electron micrography has been used, advancing the development of products that exploit structural color, such as "photonic" cosmetics. Color Color (American English), or colour (Commonwealth English), is the characteristic of human visual perception described through color "categories", with names such as red, orange, yellow, green, blue, or purple. This perception of color derives from the stimulation of cone cells in the human eye by electromagnetic radiation in the visible spectrum. Color categories and
Orange (colour) political and social movements. In the United States Army, orange has traditionally been associated with the dragoons, the mounted infantry units which eventually became the US Cavalry. The 1st Cavalry Regiment was founded in 1833 as the United States Dragoons. The modern coat of arms of the 1st Cavalry features the colour orange and orange-yellow shade called dragoon yellow, the colours of the early US dragoon regiments. The US Signal Corps, founded at the beginning of the American Civil War, adopted orange and white as its official colours in 1872. Orange was adopted because it was the colour of a