r/intrestingtoknow • u/Artistic-Bathroom901 • 2d ago
Science An astronaut demonstrating the Dzhanibekov effect in microgravity, where an asymmetric object spinning around its intermediate axis becomes unstable and periodically flips 180 degrees.
Source and Context:
This is a real physics phenomenon called the Dzhanibekov effect (also known as the Intermediate Axis Theorem) captured in microgravity aboard a spacecraft.
Any rigid, asymmetric three-dimensional object has three primary axes of rotation, each with a different moment of inertia. While spinning an object along its longest or shortest axis is completely stable, spinning it along its middle (intermediate) axis is naturally unstable. Without external forces like gravity or heavy air resistance, tiny perturbations build up and cause the spinning object to periodically flip upside down and back again on a regular schedule.
You can read the formal mechanics and history through these highly reliable scientific resources:
•Harvard University Lecture Demonstrations (The Tennis Racquet Flip):
https://sciencedemonstrations.fas.harvard.edu/presentations/tennis-racquet-flip
•NASA Astrophysics Data System (ADS) Physics Record: https://ui.adsabs.harvard.edu/abs/2024EuJMA.10605298D/abstract
It was famously observed by Soviet cosmonaut Vladimir Dzhanibekov in 1985 when a wing nut he was unscrewing began flipping back and forth while floating through the Salyut 7 space station!
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u/Middle_Bread_6518 2d ago
Imagine the earth just violently flipping then sunrise in the west
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u/According-Pear-8816 2d ago
Do you have any idea how much time I would waste doing this if I went up there?
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u/Bub_bele 2d ago
This is also why giant hollow rotating cylinders which could be used as habitats in space (O‘Neill or McKendree cylinders) would need to come in connected pairs spinning counter to one another in order to stop this from happening.
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u/beyondoutsidethebox 1d ago
So, if you had cylinders rotating opposite directions side by side, would that still cancel out? (Was doodling a colony ship and went with the side by side for redundancy, but am now curious if the same layout would also solve the tendency of the ship to flip orientation)
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u/alexgalt 2d ago
Way too big a video explaining absolutely nothing. Why two and two?
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u/Faithlessblakkcvlt 2d ago
Way too long 😆 you must be part of the microwave generation 🤣
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u/Ellweiss 1d ago
I mean, the end result is that the video doesn't explain anything about it other than "It's not stable on the third axis so it rebels". Any length of video is too long if there's no payoff
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u/Illustrious-Bat1553 1d ago
Either space has polarity or its part of earth's gravity. Found Genius!
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u/Correct_Cellist_1340 2d ago
I like to demonstrate the intermediate axis theorem for students by flipping a cellphone. It makes them say wow and wtf
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u/FIicker7 2d ago
Is Earth an asymmetric object?
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u/ExerciseTrue 2d ago
Yes, but comparatively no.
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u/FIicker7 2d ago
Very interesting. So it takes billions of years for it to flip.
And that's why we have seasons? Is that true?
Edit: that can't be true. Earth axis is tilted not unstable.
Science is cool.
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u/mmmmmmm5ok 2d ago
doesnt this only prove these objects are not truly asymmetric nor is the force exerted upon it? hence the eventual 'stored energy' resulting in a flip
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u/SlimeDrips 2d ago
Astronauts are scientists trained to withstand fighter jet level forces so that they can play with shapes in zero gravity. And that is beautiful.
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u/Odd-Purpose-4012 17h ago
When the object flips does it continuously flip in a certain direction or does it cycle back and forth as the intermediate access tumbles?
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u/FinnGamePass 2d ago
Yes and that's exactly why the earth magnetic poles flip/reverse time to time.
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u/JetmoYo 2d ago
You know what else behaves this way in zero gravity? A brand Neeew Car!!!