Created when an aging star blew off its outer layers, this blue bubble is, by chance, aligned with a foreground star, and bears an uncanny resemblance to a diamond engagement ring.
This cosmic gem is unusually symmetric, appearing to be almost perfectly circular on the sky.
Most stars with masses similar to that of the Sun will end their lives as white dwarfs; small, very dense, and hot bodies which slowly cool over billions of years.
On the way to this final phase, the stars throw their atmospheres out into the space and create planetary nebulae, colourful glowing clouds of gas surrounding the small, bright stellar relics.
This image, captured by ESO’s Very Large Telescope (VLT) in Chile, shows the remarkably round planetary nebula Abell 33, about 1,500 light-years from Earth.
Being perfectly round is uncommon for these objects. Usually something disturbs the symmetry and causes the planetary nebula to display irregular shapes.
The strikingly bright star located along the rim of the nebula creates a beautiful illusion in this VLT image. This is just a chance alignment — the star, named HD 83535, lies in the foreground of the nebula about halfway between Earth and Abell 33, in just the right place to make this view even more beautiful.
Together, HD 83535 and Abell 33 create a sparkling diamond ring.