The Helix Nebula from Hubble

This Hubble Space Telescope image showcases the details of the Helix Nebula, one of the nearest planetary nebulae to Earth. A planetary nebula forms when a medium-sized star undergoes the final stages of nuclear fusion in its core and casts of its outer layers of gas. Of particular note in the Helix is the web of filamentary "bicycle-spoke" features embedded in the colorful red and blue gas ring.

From Earth, the nebula looks like a bubble, but in reality it is a cylinder-shape pointed nearly directly toward us. A forest of thousands of comet-like filaments, embedded along the inner rim of the nebula, points back toward the central stellar remnant, a small, super-hot white dwarf.

The tentacles formed when a hot "stellar wind" of gas plowed into colder shells of dust and gas ejected previously by the doomed star. Ground-based telescopes have seen these comet-like filaments for decades, but never before in such detail. The filaments may actually lie in a disk encircling the hot star, like a collar. The radiant colors correspond to glowing oxygen (blue) and hydrogen and nitrogen (red).

See http://hubblesite.org/news_release/news/2003-11