The Making of the Rotten Egg Nebula . ... Credit Copyright: V. Bujarrabal ( OAN, Spain ), WFPC2 , HST , ESA , NASA Explanation: Fast expanding gas clouds mark the end for a central star in the Rotten Egg Nebula . ... In this case, the result is a photogenic proto- planetary nebula. ... Thick gas and dust hide the dying central star. The Rotten Egg Nebula , also known as the Calabash Nebula and OH231.8+4.2, will likely develop into a full bipolar planetary nebula over the next 1000 years. ...