Why does the clear sky appear blue? How would the sky appear in the absence of Earth's atmosphere?

(N/A) The blue colour of the sky is due to the scattering of sunlight by the molecules of gases present in the Earth's atmosphere. According to Rayleigh's law of scattering, the intensity of scattered light is inversely proportional to the fourth power of its wavelength $(I \propto 1/\lambda^4)$. Since blue light has a shorter wavelength compared to other colours in the visible spectrum, it is scattered more strongly by the atmospheric particles. In the absence of an atmosphere, there would be no particles to scatter the sunlight. Consequently, no light would reach our eyes from the sky, and it would appear black.