The sky appears blue due to a phenomenon called **Rayleigh scattering**. When sunlight enters Earth's atmosphere, it is made up of different colors with varying wavelengths. Shorter wavelengths, such as blue and violet, scatter more easily than longer wavelengths like red and yellow. Although both blue and violet light are scattered, our eyes are more sensitive to blue light, and the atmosphere absorbs some violet light, making the sky appear predominantly blue. This scattering effect is stronger when the sun is higher in the sky and weaker when it's closer to the horizon, which is why sunsets often appear red, orange, or pink.