As an expert in astronomy, I can explain the phenomenon of why stars twinkle and planets do not. The twinkling of stars, known as stellar scintillation, is primarily caused by the Earth's atmosphere. When the light from a star passes through the atmosphere, it encounters varying densities of air, which are caused by temperature and pressure fluctuations. These variations refract, or bend, the light, causing it to change direction slightly. This bending effect is more pronounced when looking at objects that are very far away, like stars, because the light has to travel through more of the atmosphere to reach the observer.

On the other hand, planets do not twinkle in the same way because they are much closer to Earth than stars. The light from a planet has to travel through less of the atmosphere, so the bending effect is less noticeable. Additionally, planets appear as small disks rather than points of light, and this larger area averages out the atmospheric distortions, making the twinkling effect less apparent.

To summarize, the twinkling effect is due to the Earth's atmosphere causing the light from distant stars to refract and change direction, which is less of an issue for closer objects like planets.

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Why Planets Don't Twinkle. Planets, just like the Sun, do not twinkle. Planets are also closer to the Earth than those distant stars, so planets appear larger in comparison. Due to the planets' apparent closeness to Earth, the light coming from these celestial bodies does not bend much due to Earth's atmosphere.read more >>