MP Board · Class 10 · Science · The Human Eye and Colourful WorldWhy do stars twinkle at night? Explain briefly.

Stars twinkle at night primarily due to the atmospheric refraction of starlight. As the light rays coming from distant stars enter the Earth's atmosphere, they pass through varying layers of air that have different temperatures, densities, and refractive indices. These layers constantly shift and cause continuous refraction of light, resulting in the apparent position and brightness of the star fluctuating rapidly, which we perceive as twinkling.