Dying stars paint some amazing pictures — colorful clouds of gas and dust that can look like a cat’s eye, an hourglass, or some other fantastic shape. Such a cosmic artwork is known as a planetary nebula. It represents the final gasp of a star that’s in the same general weight class as the Sun. When the star stops producing nuclear reactions in its core, its outer layers blow away into space. The dead but hot core zaps this expanding bubble of gas with ultraviolet energy, causing it to glow. It remains visible for perhaps tens of thousands of years. As the nebula expands, it can be sculpted into many different shapes. The simplest look like soap bubbles. These nebulae probably are the fate of single stars that rotate slowly — systems like our own Sun. The expanding bubble of gas moves outward in all directions at the same speed. Some planetaries are shaped more like an hourglass, with a lobe of gas extending from each of the star’s poles. These nebulae may be sculpted by companion star
