The Dzhanibekov Effect

Today something from the field of physics for the inquisitive: The Dzhanibekov effect, also known as the tennis racket theorem, explains an instability of rotating bodies with three different moments of inertia. The moment of inertia indicates the resistance of a body to changes in its rotational movement. It depends on the particular axis of rotation and the geometry. Understanding the dynamics of classical Hamiltonian systems is still a crucial goal with a multitude of applications that go far beyond their mathematical description. In the case of integrable systems with few degrees of freedom, an efficient approach is based on a geometric analysis to characterize the dynamic properties of the mechanical system. Such geometrical phenomena are typically the origin of the robustness of certain effects that can be observed experimentally. one of them is the so-called. Dzhanibekov effect or also called the tennis racket effect.

Janibekov effect in the weightlessness of the ISS

An excellent and detailed theoretical derivation of the phenomenon can be found here (https://arxiv.org/pdf/1606.08237.pdf). We are dealing here with one who is a little rougher, but who nevertheless explains the phenomenon. Unfortunately, some prior knowledge of the dynamics of rigid bodies is necessary here: