planetary nebulae

A planetary nebula is a beautiful, glowing shell of gas and dust ejected from a dying star similar in size to our Sun. When such a star exhausts its nuclear fuel, it sheds its outer layers into space, forming an expanding, colorful cloud. The exposed core, now a hot, dense object called a white dwarf, emits intense ultraviolet light that makes the surrounding gas glow brightly. Despite its name, planetary nebulae have nothing to do with planets; the term originated from early telescopic observations. They are a temporary phase in the life cycle of medium-sized stars before they settle into their final white dwarf state.