The apparent position of a star keeps changing slightly due to the continuously varying physical conditions of the Earth’s atmosphere. This fluctuation in the apparent position, coupled with the fact that stars are distant and approximate point-sized sources of light, causes the twinkling effect.
How does the fluctuation in the apparent position of a star contribute to the twinkling effect?
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The fluctuation in the apparent position of a star, caused by atmospheric refraction, contributes to the twinkling effect. As starlight passes through Earth’s atmosphere, encountering varying temperature and density layers, its path continuously bends. These fluctuations in the bending angles create dynamic shifts in the perceived position of the star. The constant changes in refraction result in the twinkling phenomenon, where the star appears to shimmer and vary in brightness. The apparent position’s continuous fluctuations, combined with the Earth’s atmosphere acting as a dynamic lens, lead to the twinkling effect observed when viewing stars from the surface.