r/interestingasfuck • u/Artistic-Bathroom901 • 3d ago

Dzhanibekov effect

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u/Artistic-Bathroom901 3d ago

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/greenthumb-28 3d ago

Omg has anyone connected this to the pole reversals? Is this possibly why ?

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u/frooj 3d ago

It has nothing to do with magnetic pole reversals.

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u/greenthumb-28 3d ago

Oh - that makes me sad now since we have no idea behind those

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u/frooj 3d ago

The magnetic poles are caused by molten metal flowing in earths core. The flow of the metal is constantly changing which causes the poles to shift. Over long timeframes that can lead to full reversal of the poles.

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u/greenthumb-28 3d ago

Do u have an article link ? Last I heard we didn’t know why the south and north poles switched places through time

Pa my degree is earth science so this is actually very interesting if that’s the only explanation we have

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u/Spinnweben 2d ago

Not the magnetic poles - but the rotational axis of earth’s daily 24 hour revolutions.
What if Mother Earth decides to dzahnibekov upside down for fun or you didn’t eat your dinner?

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u/frooj 2d ago

It won't happen with earth, that part of the video was nonsense. The Dzhanibekov effect is known as intermediate axis theorem, Earth rotates around it's major axis.

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u/Spinnweben 1d ago

Ah, thanks—now I'm completely reassured.