Those chalky-white mustaches that color our lips after chugging down a refreshing ice-cold glass of creamy milk is caused by the protein called Casein. Rich in calcium, Casein helps contribute to milk's white color. In addition, the cream that is found in milk contains white colored fat. The more cream in milk the more white it is. Low and non-fat milk appear more grayish rather than white because they contain less cream. Another reason milk looks white to our naked eyes is because some objects do not absorb very much light. Rather than absorb light, these objects reflect light. For instance, red colored objects reflect only red light and absorb the other colors of light in the rainbow spectrum. The molecules that make up Casein and cream reflect light. That's why milk is white. mustaches: 胡子 Casein: 干酪素 calcium: 鈣     non-fat milk: 脫脂牛奶     spectrum: 光譜 molecules: 分子