Do Stars Really Twinkle? And Other Common Scientific Misconceptions

Scientific misconceptions are everywhere, so let's debunk three of the basics. 1.) What causes the seasons? 2.) Is there gravity in space? 3.) Why do stars twinkle?

Sabrina Stierwalt, PhD
4-minute read
Episode #155

2.) There is gravity in space

Watching videos of astronauts floating around inside the space shuttle or the International Space Station, it's easy to see how this misconception arises. However, if there really were no gravity in space, how would the planets stay in orbit around the Sun? The Moon around the Earth? Satellites around the Earth?

The truth is that gravity is everywhere in space, although it varies in strength. The reason astronauts float in space is because they are falling around the Earth at the same speed as their spacecraft. Since they are experiencing the same gravity as their surroundings, they experience a relative weightlessness. They are known to be in free fall, a state that means gravity is the only force acting on them.

3.) Stars don’t really twinkle

A very popular nursery rhyme tells us that stars twinkle, but we do not know why. I would, in part, agree—I would be hard-pressed to explain to you why a star twinkles based on what we know about stars ... because they don’t really twinkle.

The reality is that they only appear to twinkle as their light travels through our atmosphere and gets refracted. The motion in the air in our atmosphere is constantly changing, even on the order of milliseconds. As a star’s light passes through that turbulent atmosphere, molecules in the atmosphere refract the star’s light in different ways from moment to moment. The “twinkling” (called scintillation) that you see arises from the slight changes in the directions from which the star’s light arrives at your eyes.

If you want to arm your kids early against this misconception, check out the astronomically correct version of Twinkle Twinkle, Litte Star from the people who bring you the Saturday Morning Breakfast Cereal comics.

Until next time, this is Sabrina Stierwalt with Everyday Einstein’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Everyday Einstein on Facebook or follow me on Twitter, where I’m @QDTeinstein. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com.

Images courtesy of Shutterstock.


About the Author

Sabrina Stierwalt, PhD

Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.

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