The Bubble Nebula

NGC 7635, also known as the Bubble Nebula, is in the constellation Cassiopeia. It lies close to open cluster Messier 52. The bubble is created by the stellar wind, moving at about 4 million miles per hour 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. The Bubble Nebula is huge at around 7 light years across. That is one and a half times the distance between our sun and the next nearest star Alpha Centauri.