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This photograph of the coil-shaped Helix Nebula is one of the largest and most detailed celestial images ever made. The composite picture is a seamless blend of ultra-sharp images from NASA's Hubble Space Telescope WATCH: HubbleMinute Video HubbleMinute: Helix Nebula   combined with the wide view of the Mosaic Camera on the National Science Foundation's 0.9-meter telescope at Kitt Peak National Observatory near Tucson, Ariz. The image shows a fine web of filamentary "bicycle-spoke" features embedded in the colorful red and blue ring of gas. At 650 light-years away, the Helix is one of the nearest planetary nebulae to Earth. A planetary nebula is the glowing gas around a dying, Sun-like star.

Q & A: Understanding the Discovery

1. 1. Why does the Helix appear to be round?




The Helix appears to be round because we are looking at one end of the nebula. It is actually a trillion-mile-long tunnel of glowing gases.

2. 2. What are the features that look like bicycle spokes?




These features are a forest of thousands of comet-like tentacles that are embedded along the inner rim of the nebula. The tentacles point toward the central star, which is a small but super-hot white dwarf [white dot in center of nebula] that seems to float in a sea of blue gas. These tentacles formed when a hot "stellar wind" of gas plowed into colder shells of dust and gas ejected previously by the doomed star. These comet-like tentacles have been observed from ground-based telescopes for decades, but never have they been seen in such detail. They may actually lie in a disk encircling the hot star, like an animal's collar.