If the earth had no atmosphere, then the colour of the sky would be ______

The Correct answer is black.

Key Points

• In the absence of an atmosphere, the sky would appear black instead of its usual blue color.
• This is because there would be no air molecules to scatter the sunlight, a phenomenon known as Rayleigh scattering.
• Rayleigh scattering is responsible for scattering shorter wavelengths of light, such as blue, more than longer wavelengths.
• The scattered blue light is what makes the sky appear blue to our eyes when the sun is up.
• Without an atmosphere, sunlight would travel directly to the surface without scattering, leaving the sky dark and black, similar to how it appears from space.

 Additional Information

• Blue
  • The sky appears blue because of the scattering of sunlight by the Earth's atmosphere.
  • The shorter blue wavelengths are scattered in all directions by the air molecules, making the sky look blue from the ground.
• Yellow
  • The sky can appear yellow during sunrise or sunset due to the scattering of longer wavelengths of light, such as red and yellow.
  • This occurs when the sun is low on the horizon and the light has to travel through more of the Earth's atmosphere.
• Red
  • The sky can appear red during sunrise or sunset, similar to yellow, but with even more scattering of shorter wavelengths.
  • This is often seen when there are particles or pollutants in the air that enhance the scattering effect.