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Stars twinkle but planets do not twinkle because
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- they emit light of a constant intensity
- their distance from the earth does not change with time
- they are very far away from the earth resulting in decrease in intensity of light
- they are nearer to the earth and hence we receive a greater amount of light and therefore minor variations in intensity are not noticeable
- they emit light of a constant intensity
Correct Option: D
Stars twinkle because they are point light sources. Passing through the atmosphere, the small beam of light constantly shifts by bouncing off particles in the air. The much closer planets appear instead as tiny disks in the sky. Their apparent sizes are usually larger than the pockets of air that would distort their light, so the effects of scintillation are negligible. Being closer, planets appear as discs, with the shifting of light from one side cancelling out the other.
