Light from the Sun appears white but it actually consists of many different colours. We can see these different colours of light in a rainbow or when white light passes through prism. As the white light from the Sun travels through the Earth’s atmosphere, it collides with particles of air. The different colours, or wavelengths, of light are scattered by these collisions by different amounts. Blue light (shorter wavelengh) is scattered more than red light (longer wavelength). So, when the Sun is high in the sky, blue light is scattered in all directions as sunlight passes through the atmosphere and we see the sky as blue.