Examples of the Beauty and Variety of Planetary Nebulae

Examples of planetary nebulae. Some are spherical (a) or helical (b), others have bipolar shapes (c), and still others are rather irregularly shaped (d). It is not entirely clear what causes this variety of shapes. Astronomers suspect that the existence of a close stellar companion to a nebula's progenitor star and a fast stellar wind that pushes on the nebula are at least in part responsible for some of these unusual shapes. Image Credit: a and d. Howard Bond (Space Telescope Science Institute), Robin Ciardullo (Pennsylvania State University), and NASA. b. Raghvendra Sahai and John T. Trauger (Jet Propulsion Laboratory), the Wide Field and Planetary Camera 2 Science Team, and NASA. c. Bruce Balick (University of Washington) and NASA.

The Cat's Eye Nebula is another example of highly complex planetary nebulae. The nebula's intricate structure includes several gaseous shells blown off at different times, jets of high-speed gas, and a series of bright, gaseous knots which are formed when high-speed gas collides with slower-moving gas. The nebula is 3,000 light-years distant and lies in the constellation Draco (the Dragon). Image Credit: J. Patrick Harrington and Kazimierz J. Borkowski (University of Maryland), and NASA.