A soap bubble in space

A real gaseous bubble blown by a dying star wanders alone, floating in space. PN G75.5+1.7, known as the Soap Bubble Nebula, sports an extraordinary spherical symmetry (just like the bubbles children play with) and was created over 20,000 years ago by a star similar to the Sun, at the end of its life. Having exhausted the nuclear fuel in their nuclei, the medium-small stars expel the outer gaseous layers and collapse under the effect of their own gravity until they become dense and warm white dwarfs. The material ejected from the star impacts interstellar gas and dust, while the hot star core illuminates the surrounding gas, leading to the formation of colored clouds, known as planetary nebulae.

The cosmic spectacle is short-lived: within a few thousand years this beautiful planetarium is destined to disappear forever in the dark night. 

Credit: T. A. Rector/University of Alaska Anchorage, H. Schweiker/WIYN and NOAO/AURA/NSF