Bubble Nebula Star Disc for the Homestar Flux. The Bubble Nebula – NGC 7635, also known as the Bubble Nebula is in the constellation Cassiopeia. It lies close to the direction of the open cluster Messier 52. The “bubble” is created by the stellar wind from a massive hot, young central star. The nebula is near a giant molecular cloud which contains the expansion of the bubble nebula while itself being excited by the hot central star, causing it to glow. It was discovered in 1787 by William Herschel. When projected it creates a dazzling show of colors. This disc will NOT fit other brands of home planetariums.