The most detailed image of the nebula named for the dreadful Greek creature that turned men into stone was taken by the European Southern Observatory's (ESO) Very Large Telescope (VLT) in Chile. The Medusa Nebula is progressing in its own demise as the outer layers are sloughed into space, creating the colorful cloud in the photo, according to a press release.

The planetary nebula is named after the Gorgon Medusa. It is also known as Sharpless 2-274 and is located in the constellation of Gemini (The Twins). The Medusa Nebula spans approximately four light-years and lies at a distance of about 1500 light-years. Despite its size it is extremely dim and hard to observe.

Medusa was a hideous creature with snakes in place of hair. These snakes are represented by the serpentine filaments of glowing gas in this nebula. The red glow from hydrogen and the fainter green emission from oxygen gas extends well beyond this frame, forming a crescent shape in the sky. The ejection of mass from stars at this stage of their evolution is often intermittent, which can result in fascinating structures within planetary nebulae.

The nebula is also referred to as Abell 21 (more formally PN A66 21), after the American astronomer George O. Abell, who discovered this object in 1955. For some time scientists debated whether the cloud could be the remnant of a supernova explosion. In the 1970s, however, researchers were able to measure the movement and other properties of the material in the cloud and clearly identify it as a planetary nebula.

This image uses data from the FOcal Reducer and low dispersion Spectrograph (FORS) instrument attached to the VLT, which were acquired as part of the ESO Cosmic Gems program.