Astronomers using NASA's Hubble Space Telescope have seen clearly for the first time the shockwaves produced during the formation of a planetary nebula. The new image provides confirmation of the complex gas structures predicted by theory, and may portend how our Sun's death will unfold.

Spying on the Calabash Nebulaalso dubbed the Rotten Egg Nebula for the large amount of sulfur compounds it containsa team of Spanish and American researchers studied how gas expelled by the dying star interacts with surrounding matter. They found that, as expected from computer calculations, the high-speed collisions result in the formation of shock fronts, which heat the surrounding gas. In the image at the right, the gas ejected from the star is shown in yellow and the heated gas appears in blue. The dying star itself lies shrouded in a dusty band between the two streams of flowing gas.

"We can see how the shocks have broken through the surrounding gas," team member Valentin Bujarrabal notes. "We believe we can see both of the shock components we expectthe forward and the backward shockwaves." Much of the gas flow apparent in the Hubble image seems to have come from a sudden acceleration that took place a mere 800 years ago. In another 1,000 years, the team suspects, this proto-planetary nebula will be fully developed.