Why Do Stars Twinkle?

Kids love to sing the nursery rhyme “Twinkle, twinkle, little star…” And kids are really right, for not only they but everyone “wonder what you are”. For like diamonds in the sky, they sparkle and glow. So do stars naturally flicker? If not, what makes them twinkle?

Stars are objects in the space that are balls of gases and fire. In our view here on Earth, they appear to twinkle. Twinkling of stars, scientifically referred to as stellar scintillation or astronomical scintillation, is due to the presence of thick layers of moving air in the Earth’s atmosphere through which we see them.

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All stars, except for the Sun, appear to be tiny dots in the sky because of their relative distance to us. As the light of the stars travel through several layers of turbulent air and impurities in the atmosphere, it is bent or refracted many times and in random directions. The total different refractions for star results to “sparkling” and “gleaming” which our eyes interpret as “twinkling.”

Stars closer to the horizon appear to twinkle more than those overhead of us. This is because these stars have travelled to more layers, and consequently refracted more times, than those just above us. That is why that the Sun that is nearest to us does not twinkle at all. Further, planets do not twinkle. They are so close to us that their twinkling is not prominent, except maybe when the air is extremely turbulent. So the next time you are looking out at the sky and see a “star” that does not twinkle, chances are that you are viewing a planet.

 

Assuming we are in the outer space and are star gazing. Do you think stars will twinkle? No, it is because the space has no atmosphere. Even with moons and planet with no atmosphere, twinkling is not possible. That is why, telescopes in the outer space, just like the Hubble telescope, are successful in giving precise astronomical data because of the absence of twinkling that gives better images of objects in space.