What phenomenon is responsible for the twinkling of stars?

The correct answer is Refraction. 

• The atmospheric refraction is responsible for the twinkling of stars.
• As the light from the stars enters the earth's atmosphere it suffers refraction and causes the twinkling of light. 

Key Points

• Refraction- When a light ray travels from one transparent medium to another transparent medium then it deviates from its original path and this phenomenon is called Refraction.
  • For example- when light travels from the Rarer medium (Air) to the Denser medium (Water) is deviates towards the Normal.
• Laws of refraction
  • The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant.
  • The Normal, Incident ray, Refracted ray lie on the same plane at the point of Incidence.   

​​ Additional Information

• Diffraction- The bending of a light ray from its path after striking an obstacle.
  • Diffraction is the result of interference.
•  Dispersion- The separation of visible light into its different colours is known as dispersion, Example- Prism( splitting of white light into seven colours).
• Scattering - It is the Phenomenon in which light gets deviated from its straight path after striking the obstacle like dust or gas molecules, water vapour, etc.