The sky is blue because blue light resonates with the air molecules and therefore has a higher scattering intensity (due to Raleigh scattering). Thus, we see blue light when we look at the sky (any light that we see, while not looking directly at the sun, must have been scattered). Is this right so far? If so, I am still confused by the following. Say that only red light and blue light are coming in. The red light is something like half as energetic as the blue light. How, then, can the blue light be scattered more than twice as intensely? That would seem to violate the conservation of energy. Is the answer that the rest of the red light is simply transmitted, and not scattered? Now, I still don't get why sunsets would be red. The sun is red because it emits red light most intensely, right? (It would be red if we looked at it from space). People constantly describe the sunset as red because the light has to pass through more atmosphere, so most of the blue light is "scattered out". Don't we still see that light? (We see both the scattered light and the transmitted sunlight, so we see blue+red+everything else?). I think this might be related to my second paragraph. Thanks!