A Stellar Bubble: When an ageing star shed its outer layers, this blue bubble was left behind.

This eye-catching image of the planetary nebula Abell 33 was taken by astronomers using the European Southern Observatory’s Very Large Telescope in Chile. Created when an ageing star blew off its outer layers, this beautiful blue bubble is, by chance, aligned with a foreground star. This cosmic gem is unusually symmetric, appearing to be almost perfectly circular on the sky.

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