Here's why:

* Planetary Nebula Formation: Planetary nebulae form when a star like our Sun runs out of fuel in its core. The outer layers of the star are ejected, creating a beautiful, expanding shell of gas.

* White Dwarf Core: The remaining core of the star, which is incredibly dense and hot, is what we call a white dwarf. It's essentially the exposed core of the star that was once hidden beneath layers of gas.

* Evolution: White dwarfs are the end product of the evolution of stars like our Sun. They slowly cool over billions of years, eventually becoming black dwarfs, which are incredibly faint and difficult to detect.