Why Stars Twinkle

“Twinkle, twinkle, little star. How I wonder what you are? Up above the world so high, like a diamond in the sky.” Many children have been lulled to sleep by the simple lyrics of this song about the beauty of the stars winking at mere mortals on Earth. On a clear night, people who are fortunate enough not to live in a polluted climate get to see the wonders of a sky filled with stars, twinkling in the sky.

From the beginning of time, the stars have elicited various emotions in the hearts of individuals, from love to wishful thinking. Some have even pondered the question of why stars twinkle in the first place. However, the answer is more scientific than the response many of us got from our parents when we were children.

In simple terms, they twinkle because of disturbances in the Earth’s atmosphere. The atmosphere is made of multiple layers, and each of these layers is a different temperature and has a different density. Light from the stars bend, refracts, as it passes through each layer of the atmosphere, making the light shoot randomly in the sky. Refraction looks like twinkling to the human eye.

Refraction is not as hard a concept as it may seem. It actually occurs when light has to pass from one substance to another. For example, when a straw is placed in a glass of water, look at the side. When a person looks at a straw through from the side, it looks as if it is broken or bent. That’s refraction.

The stars’ distance from planet Earth affects how much they twinkle in the sky. If the star is closer to the horizon, it will appear to twinkle more because a greater amount of atmosphere lies between you and the star. They look like points of light in the night sky. An easy way to differentiate between stars and planets is that, unlike stars, planets don’t twinkle because they are closer to the Earth’s atmosphere. The fluctuation is not great enough to affect the light refracting from them.

Star gazers don’t always get the best look at these twinkling stars when they look through their telescopes if they are on the ground. The reason for this is that atmospheric distortion occurs, making the image look blurry. To get a good look at stars in the night sky, it is better to go to an observatory located on a mountaintop because there is less atmospheric distortion.

Of course, scientific explanations may present the logical reason for twinkling stars. There is nothing like seeing this natural phenomenon to create moods of childish fantasy or romance.


MIRA: Field Trip to the Stars

Figure: Why stars twinkle: Atmospheric distortion of light