NGC6888 – The Crescent Nebula

The Crescent Nebula, in the constellation Cygnus, is the result of a red giant star that used up all its hydrogen fuel and expelled its outer shell of gas. About 250,000 years ago, the star evolved into a Wolf-Rayet type and began producing a strong stellar wind as it burned heavier elements. The wind collided with the hydrogen cloud from the first phase, compacting it into complex shells. Strong ultraviolet radiation ionizes the hydrogen gas, causing it to glow red. The star, WR136, will likely explode as a supernova within the next million years.

This image was made with a color camera using a clear filter, plus additional subframes with Hydrogen-alpha and Oxygen-iii narrowband filters.

The monochrome Hydrogen-α image at the bottom of the page shows a closeup of the nebula through a different telescope and camera.

Hydrogen-alpha monochrome

This image illustrates how well a Hydrogen-α filter can capture the faint nebulosity near the Crescent Nebula. This was captuted in 2006 at our former observatory using a telescope and camera with a much smaller field-of-view.

Updated May 23, 2023