Question

What is the primary cause of the twinkling or shimmering effect observed in some stars?

1. Their rapid rotation
2. Atmospheric distortion and turbulence
3. Changes in their intrinsic brightness
4. Changes in their intrinsic brightness

• A. All
• B. 1, 2
• C. 1, 3
• D. 2 only

Answer 1

Answer:

D. 2 only

• The twinkling or shimmering effect, known as "Stellar scintillation," occurs when stars are observed  from the surface of the Earth.
• It is primarily caused by atmospheric distortion and turbulence.

Atmospheric Distortion:

• When starlight passes through the Earth's atmosphere, it encounters different layers of air with varying temperatures, densities, and refractive indices.
• These variations in the atmosphere's properties cause the starlight to refract or bend as it travels toward the observer on the ground.
• This bending of light is what we perceive as twinkling.

Turbulence:

• The Earth's atmosphere is not a static, homogenous medium; it is constantly in motion due to various factors like wind and temperature gradients.
• This atmospheric turbulence leads to fluctuations in air density and refractive index.
• As a result, the path of starlight becomes irregular, with some portions bending more than others.
• These fluctuations in the bending of light create rapid changes in the star's apparent position and brightness as seen from Earth.