The Crescent Nebula taken from Al Sadeem Observatory last July 17, 2018 (Image Credit: Aldrin B. Gabuya/Al Sadeem Astronomy)
The Crescent Nebula (known as NGC 6888) is a spectacular emission nebula situated about 5000 light-years away from Earth in the constellation of Cygnus (the swan). The name was derived from the well-defined crescent shape; some considered it as the “Euro Sign Nebula” resembling the shape of the Euro sign. It was discovered in 1792 by the British astronomer Friedrich Wilhelm Herschel.
This emission nebula is an arc of interstellar gas being illuminated by a bright evolved Wolf-Rayet Star WR 136 (HD 192163) in which its fast stellar wind from its outer layers collides with its stellar material ejected during its earlier phase, producing a shell structure with scorching X-ray emitting temperatures generated from shock waves. The fast stellar wind ejection takes place every 10,000 years until WR 136 would burn out its fuel in a supernova explosion.
With an apparent magnitude of +7.40, it is quite a faint deep-sky object to be seen with the naked eye. We would need 6 – 8 (even up to 10) inches telescope under a clear, very dark sky in observing the nebulous crescent, and more preferably do long exposure photography (to reveal at its full optical extent). The nebula is located approximately 2.7 degrees southwest of the bright star Sadr.
Nemiroff, R., & Bonnell, J. (2016, June 10). APOD: 2016 June 10 – NGC 6888: The Crescent Nebula. Retrieved from NASA Astronomy Picture of the Day: https://apod.nasa.gov/apod/ap160610.html
Ventrudo, B. (2012, June 15). The Crescent Nebula. Retrieved from One Minute Astronomer: https://oneminuteastronomer.com/5995/crescent-nebula-ngc-6888/
Wikipedia contributors. (2018, March 25). Crescent Nebula. In Wikipedia, The Free Encyclopedia. from https://en.wikipedia.org/w/index.php?title=Crescent_Nebula&oldid=832378441