A large, ancient planetary nebula in Gemini, roughly 1,500 light-years away. Planetary nebulae form when a sun-like star reaches the end of its life and gently sheds its outer layers into space, leaving behind a hot white dwarf at the centre. The Medusa is one of the oldest and largest known planetary nebulae — its material has been expanding for so long that the shell has become extremely faint and diffuse, with a complex braided filamentary structure that gives it its mythological name.

The Medusa's low surface brightness makes it a demanding target. Long exposures through narrowband filters are needed to capture the delicate oxygen and hydrogen emission that trace out its tangled filaments.