Question

why don't the planets twinkle?

Answer 1

actually planets and star both doesn't twinkle,because the Star are too much far from earth then the planets so the light from the stars come to us by atmospheric reflection
and it seems to be twinkle. also planets have not it's own light so it not seems to be twinkle.

Answer 2

Hello friend thanx for the question, let me tell you the stars twinkle because of atmospheric refraction, atmospheric refraction is the refraction which simply occurs in the atmosphere. Stars appear to twinkle as the light from them reaches our eyes after refraction from the layers of atmosphere. Since there is no distinct boundary in the layers of atmosphere the light appears to bend smoothly. Well the rapid temperature and density variation in the atmosphere makes the stars to twinkle, but when we take the example of planets which are extended sources of light we can see that they don't twinkle! Their apparent image is formed within the radius of actual image! Also the intensity of light from the planet makes the light to bend least.