2 ms·

I wonder if it's reproducible in vacuum or the air is necessary to destabilize it?

• bunderbunder 1y ago
  It's about angular momentum and happens whenever the axis of rotation differs - even slightly - from the semi-major axis. Interaction with a fluid is not necessary. You can demonstrate it at home with your smartphone (or, more canonically, a tennis racket), and see for yourself that the tumbling happens much too quickly to be explained by whatever force the air is imparting.