Why Stars Twinkle but Planets Don’t
Explain why the planets do not twinkle, but the stars twinkle.
Why Stars Twinkle but Planets Don’t
The twinkling of stars is a phenomenon observed due to atmospheric refraction.
The physical conditions of the atmosphere do not remain constant, and so the refractive index of the air continuously changes.
This leads to continuous change in the direction of the light coming from stars as the changing indexes lead to different extents of bending of light.
Due to this, the amount of light entering our eye continuously changes, leading to our perception that the star sometimes appears brighter and sometimes fainter, I.e., twinkling.
Now, we can understand the phenomenon of planets.
Planets are extended sources of light, i.e., they can be thought of as a combination of many point sources of light.
So, every beam of light coming from each of the comprising point sources experiences different extents of bending.
But what happens is that the extent of bending of all the rays combined averages out to zero.
So, they do not twinkle.
– Written By SHRUTI SINGH
The phenomenon behind the twinkling of stars is known as atmospheric refraction. ’
When the light from the stars enters the atmosphere of earth, the light from stars undergoes the refraction due to the different density of atmospheric gases (air) on different levels before coming to us. So, the refractive index changes continuously and refracts the light coming from the stars in different amounts. In this way, the starlight reaching our eyes increases and decreases due to the uneven density of atmospheric air present in its paths. That’s why they appear to twinkle.
Planets do not twinkle because they are larger and very close to us in comparison to stars, which are far away from us and large. So, as we know, there are many other planets in our solar system. So, planets can be taken as a collection of a large number of point-sized sources of light. As they are in the group, the starlight that comes from them to our eyes as an individual, which gives that twinkling effect, will be averaged out of zero, which nullifies the twinkling effect of each other.
– Written By Aruja
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