What is Blue?
{{colorswatch|blue|0000FF}} [[File:Flag of Scotland.svg|thumb|right|Flag of [[Scotland]] has a blue background]] [[File:The Earth seen from Apollo 17.jpg|thumb|left|250px|The famous ''Blue Marble'' [[photograph]] of [[Earth]], taken by [[NASA]]'s [[Apollo program|Apollo]] 17]] [[File:Trees rising out of Cheow Lan Lake, blue sky, eternal summer in Surat Thani.jpg|thumb|The sky of the rising the summer the lake in Surat Thani Lake, [[Thailand]]]] '''Blue''' is one of the [[color]]s of the [[rainbow]] that [[people]] can see. It is one of the [[primary colors]] (colors that can be mixed with other colors) of [[light]], along with [[red]] and [[green]]. Apart from indigo and violet, it has the shortest [[wavelength]] of colors in the rainbow (about 470 [[nanometer]]s). Blue [[paint]] can be made by mixing [[magenta]] and [[cyan]] paint. Blue is the color of the [[Earth]]'s [[sky]] and [[sea]]. [[Earth]] looks blue when seen from [[outer space]] by [[astronaut]]s. It is the color of [[cold]], [[Extraversion and introversion|introversion]] and openness, by opposition to [[Red|the red]], which is the color of [[warm]], [[Extraversion and introversion|extroversion]] and the closure. In [[alchemy]], blue is also the color of the [[Extraversion and introversion|warm introvert]] (blue fire), by opposition to [[Red|the red]], which is the color of the [[Extraversion and introversion|warm extrovert]] (red fire). Blue is usually associated with [[masculinity]], [[harmony]], [[conservatism]], [[liberalism]], the [[cold]], [[sadness]], [[calmness]] and [[royalty]]. {{-}} == Meaning of blue == The color blue is sometimes associated with [[sadness]], which may be where the name of the music style [[Blues|The Blues]] comes from. Blue is a color of the Jewish religion. In Western cultures since the 1940s, blue is associated with men/boys, while [[pink]] is associated with women/girls. Before the 1940s, it was the other way around in some countries, so blue was for women/girls and pink was for men/boys. Nobody knows exactly w