Some of the most photogenic objects in the universe are planetary nebulae. As a star runs low on the fuel it uses to power its fusion furnace, the star starts to shed the outer layers of its atmosphere. The gas is expelled into space at several kilometers per second. This will ultimately bare the star’s core. Now classified as a white dwarf the core is no longer creating energy. Once exposed, the core’s remaining heat energizes the surrounding expelled gas causing it to glow. It is these glowing shells of gas that we call planetary nebula. They come in all shapes and sizes. There are several theories accounting for the varied shapes. Some appear to be shaped by the original star’s magnetic fields and some appear to be shaped by companions to the original star (planets or secondary stars).
In a relatively short time (10,000 years or so) the dwindling ultraviolet output fails to energize the increasingly distant shells of gas. Eventually, the planetary nebula dissipates and the white dwarf remains alone and spends the rest of its existence slowly cooling, becoming less and less visible.
Known as the Dumbbell Nebula due to the brightest portion’s pinched shape, this planetary nebula is located in the northern constellation Vulpecula (The Little Fox) at an estimated distance of 1360 ly. It is the first planetary nebula discovered, being cataloged by Charles Messier in 1764. Viewed under dark skies, it is bright enough and large enough to be seen with binoculars. This image is sixty 60 second exposures through a Hydrogen Alpha filter.
The same image stretched further and viewed as a negative reveals an additional more distant shell of gas.