What is the proof that electron degeneracy pressure exists in earth and other planets (including asteroids)?

Because of the Pauli exclusion principle, which forbids multiple electrons from existing in the same quantum state, electron degeneracy pressure keeps the electron shells of two atoms from overlapping. An atom is made up of a small nucleus encircled by electron shells.

The electron degeneracy pressure separates the atoms in any solid object, which is why you don't fall through the floor.

Neutron stars and black holes are the only objects in which electron degeneracy pressure is absent. When electron degeneracy pressure is overcome by gravity, the object collapses, the protons become neutrons, the electrons are expelled, and the nuclei combine.

The only known object that can withstand the electron degeneracy pressure caused by collapse is the core of a large star that has run out of nuclear fuel. This type of collapse can only occur in very massive objects.

Therefore, we can be positive that all objects, except for black holes and neutron stars, have electron degeneracy pressure because they are too massive for gravity to overcome.

Electron degeneracy pressure is observed in Earth and other celestial bodies through the exclusion principle, preventing electron overlap in atomic structures. This pressure supports celestial objects against gravitational collapse, evident in stable structures like planets and asteroids.