Located in the constellation Cassiopeia, the Bubble Nebula complex is actually a nest of three bubbles that surround a very hot massive star. Much like the Orion Nebula, the gas seen is energized by the light from the bright star that is embedded within. In this case, though, the star's outflow is blowing a bubble in the surrounding gas. The bubble itself is about 10 light years in diameter, and lies 11,300 light years from us.