In the absence of atmosphere, the colour of the sky would be:

The correct answer is black.Key Points

• The reason behind the blue colour of the sky is Rayleigh scattering, which occurs due to the scattering of sunlight by the molecules in the Earth's atmosphere.
• As there is no atmosphere in the absence of it, there would be no scattering of sunlight, and the sky would appear black.
• Red and white colours are also not possible as they are also the result of scattering of light in the atmosphere, and in the absence of it, the sky would not appear in any colour.
• The black colour of the sky would also mean that stars would appear brighter and the contrast between them and the sky would be much clearer.
• The concept of the sky being black in the absence of atmosphere is also applicable to other planets and moons without an atmosphere, such as the Moon and Mercury.

Additional Information

• The scattering of light by particles up to a tenth of its wavelength that happen in its path without causing an energy loss or wavelength change is known as Rayleigh scattering.
• Red colour appears during sunrise and sunset when the sunlight passes through more atmosphere, scattering the shorter blue and green wavelengths and allowing the longer red wavelengths to pass through.
• White colour appears when sunlight is scattered equally by all the molecules in the atmosphere, making the sky appear as a bright white.