Photograph
The Lobster Claw (Sh2-157) and Bubble (NGC 7635) Nebulae
A cosmic region of ionized gas in the constellation Cassiopeia, located about 11,000 light-years away. The image captures the delicate sphere of the Bubble Nebula, blown by the stellar wind of a massive star, alongside the vast emission structure resembling a lobster's claw.
Beyond the frame
The Bubble appears almost perfectly round, yet the star inflating it is not located at its geometric center. The reason is that the stellar wind expands into a cloud of uneven density and meets different resistance in each direction. The circular outline is therefore not a quiet sphere, but the front of a powerful outflow colliding with its surroundings.