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) problems. Orange also had and continues to have a political dimension. Orange serves as the colour of Christian democratic political ideology, which is based on Catholic social teaching and Neo-Calvinist theology; Christian democratic political parties came to prominence in Europe and the Americas after World War II. In Ukraine in November–December 2004, it became the colour of the Orange Revolution, a popular movement which carried activist and reformer Viktor Yushchenko into the presidency. In parts of the world, especially Northern Ireland, the colour is associated with the Orange Order, a Protestant fraternal organisation and relatedly, Orangemen, marches and other social