The Crescent and the Soap Bubble

This wide field takes in two bubbles blown by dying stars, some 5,000 light-years away in the constellation of Cygnus. The more obvious one, shaped like a crescent, is the Crescent Nebula (NGC 6888).

This shell of gas is the work of a rare and colossal star, hidden at its centre: of the Wolf-Rayet type, some twenty times heavier than the Sun and nearing the end of its life. It blows a wind so fierce that it catches up with and slams into the material the star had released earlier; from that collision the glowing shell is born, and it is still swelling today. Within a few hundred thousand years, the star is expected to explode as a supernova.

Just to the lower left of the Crescent, far more discreet, floats an almost perfect sphere: the Soap Bubble Nebula. So pale that you really have to hunt for it, even a trained eye sometimes struggles to find it; it shows best at full resolution, reachable through the AstroBin button beneath the image. It is another dying star, but of a more modest kind, gently breathing out its outer layers, as our own Sun will one day. So faint that it went unnoticed until 2007, when an amateur astronomer, Dave Jurasevich, tracked it down in his own images. Two stellar deaths side by side, two opposite fates.