The light from the sun appears to be white. That light travels in a straight line until something in its path causes it to reflect, bend or scatter. It appears to be white, but is really made up of all the colours of the rainbow. That light travels in waves. Some waves are short and choppy, other waves are lazy and long. Blue is the shortest of all the light waves. When the white light from the sun hits the Earth's atmosphere, it is scattered. As blue is the shortest light wave, it is scattered more than all the other colours, making the sky appear to be blue.