SUNSET: 
0
Photographer:
Jon Greif
Location of Photo:
Alpine, CA, USA
Date/Time of photo:
July 4-5, 2024, between 10 pm and 3 am PDT
Equipment:
Takahashi FSQ-85 refractor, ZWO ASI 533 MC pro camera, Rainbow Astro RST-135 mount, ZWO 30 mm guide scope, ASI 290MM guide camera, ASIAIR Plus capture computer, Pixinsight 1.8.9 processing software.
Description:
The Crescent Nebula, also known as NGC 6888, is a cosmic bubble blown by winds from a massive star in the constellation Cygnus, about 5000 light-years away from Earth. It was discovered by William Herschel in 1792. It is formed by the fast stellar wind from a Wolf-Rayet star colliding with and energizing the slower moving wind ejected by the star, itself, when it became a red giant around 250,000 years ago. The result of the collision is a shell and two shock waves, one moving outward and one moving inward. The inward moving shock wave heats the stellar wind to X-ray-emitting temperatures. The image is from 3.5 hours of exposure time overnight in our backyard in Alpine (after watching fireworks).
