Sh2-274, as listed in the Sharpless catalog, is commonly known as the Medusa Nebula. It is located in the constellation Gemini approximately 1,500 light-years distant. Most of the celestial objects imaged by amateurs have been known dating back to the eighteenth century. The Medusa Nebula is an exception. It was first discovered by George O. Abell in 1955. The filaments of glowing gas winding through the nebula suggested the "serpent hair" of Medusa in ancient Greek mythology. Until the early 1970s the nebula was believed to be a supernova remnant. In 1971, astronomers in the Soviet Union analyzed expansion velocities and thermal characteristics and determined that most likely it is a planetary nebula.
The image above is known as a mapped, or false, color image and was acquired using narrowband filters. It was assembled using the standard Hubble palette with SII mapped to Red, Ha mapped to Green and OIII mapped to Blue. The stars were overlaid with bi-color data from a Ha,OIII,OIII image. The near true color (Ha/OIII/OIII) version of the image may be viewed here.