Twinkle Twinkle Little Star: The Science Behind It.
Twinkle, twinkle, little star, how I wonder how you do it? That's right. From a very young age, we're continuously taught that stars twinkle, much like, well, diamonds in the sky.
But have you ever wondered why stars twinkle? And why the same can't be said for planets?
Twinkle, twinkle, celestial objects
A scientist however, does not classify it as twinkling. Rather, a scientist refers to the phenomenon of a star twinkling down on Earth as stellar scintillation. And according to them, stars actually don't twinkle. Instead, they are constantly shining with brightness.
This happens when a light from star far away reaches our own planet. As it does, it then passes through our atmosphere that then bends each ray of light. This process is called refraction and can be observed by shining a light through a transparent object, like glass.
And so, as the light from the star enters our atmosphere, the air from it bends the rays of light. But the process doesn't stop there. The light also passes through the different areas in our atmosphere, some with more or less density than others. This process continuously repeats as light passes through, pushing the rays into a zigzag direction while being refracted again and again.
This makes the light that reaches our eyes constantly changing, each refracted in a different way than the last. The effect is a light that to our viewpoint appears to be constantly shifting from bright to dim. (https://www.irishexaminer.com/breakingnews/lifestyle/features/appliance-of-science-why-do-stars-twinkle-941781.html) This is what we know as twinkling.
The view from up above
Astronauts however, have a different view of stars. Since they're in space, a place where no air molecules exist, stars appear to constantly shine when they look at them.
But why don't planets shine?
It's simple. Most planets have a broader shape than stars, which means that there's a wider field of light reaching our eyes coming from them. And while of some of these rays get refracted, majority don't, since these light rays tend to cancel each other out as they're traveling through space. This is why planets don't "twinkle" from our point of view and just shine constantly.