Crescent Nebula (NGC 6888)

The emission nebula NGC 6888, commonly known as the Crescent Nebula, is a striking bubble of glowing gas located in the constellation Cygnus. It was created by the powerful stellar winds of a massive and extremely hot Wolf–Rayet star nearing the end of its life. During this phase, the star ejects material at tremendous speeds (often thousands of kilometers per second). These fast winds collide with slower material expelled earlier in the star’s evolution, compressing and heating the surrounding interstellar gas and forming the shell structure visible in the nebula.

The resulting bubble of ionised gas spans roughly 7 parsecs (or 25 light-years) and is located approximately 1.5 kiloparsecs (or 5000 light-years) from Earth. The delicate arcs and filamentary structures seen in the image trace shock fronts where the stellar wind collides with previously ejected material and the surrounding interstellar medium. These turbulent interactions create regions of varying temperature, density, and ionisation that give the nebula its complex appearance.

The image was captured from Leysin, Vaud (Switzerland) using a Celestron C14 Schmidt-Cassegrain reflecting telescope with an aperture of 356 mm and a focal length of 3.9 m. The image was obtained using narrowband filters targeting the Hydrogen-alpha, Sulfur-II, and Oxygen-III emission lines, combined with normal RGB exposures for the stars.
 
Aurel Schneider 2025