Labels:text | screenshot | font | number OCR: PLANETARY NEBULA A PLANETARY NEBULA is an expanding shell of gas thrown off by a star that is in a late stage of stellar evolution. Viewed through a small telescope, the shell of gas can give the star the appearance of a planet. The gas expands for about 35,000 years until it is too thin to be visible. Planetary nebulas come in a variety of shapes, including rings, bubbles, and hourglass shapes.
