Medusa Nebula AKA Abell 21 and Sharpless 2-274.

The Medusa Nebula is a planetary nebula in the constellation of Gemini. It is also known as Abell 21 and Sharpless 2-274. It was originally discovered in 1955 by University of California, Los Angeles astronomer George O. Abell, who classified it as an old planetary nebula.

Narrrow-band image processed in the Hubble palette. Red=SII, Grenn=SII, and Blue= OIII. 6 integration time.