Bubble nebula (NGC 7635) with surrounding nebulosity. North is at top. The Bubble itself is in the bright orange patch just left of centre, just left of the bright blue star. It is a 10 light year wide shell of gas that has been excavated by a powerful star within it. The Bubble nebula lies around 11,000 light years from Earth in the constellation Cassiopeia. At upper left, above and left of the Bubble in line with it and the bright star, is the dense open star cluster M52. This cluster is some 5000 light years away, also in Cassiopeia. Photographed by the 1.22-metre Oschin Telescope at Mount Palomar Observatory, California, USA.