NGC 7635: The Bubble Nebula . ... WFPC2 , HST , NASA Explanation: What created this huge space bubble? A massive star that is not only bright and blue, but also emitting a fast stellar wind of ionized gas . The Bubble Nebula is actually the smallest of three bubbles surrounding massive star BD+602522, and part of gigantic bubble network S162 created with the help of other massive stars. As fast moving gas expands off BD+602522, it pushes surrounding sparse gas into a shell . ...