dark nebula

Dark Nebula

Nebulas are glowing clouds of dust and gases which are present in this vast multiverse ....

 Unlike other nebulas which are luminous there are nebulas which are dark and completely opaque known as absorption nebula or dark nebula... 

A dark nebula is a type of nebula that is so dense that it conceals the light from celestial objects behind it, such as background stars and emission or reflection nebula. The extinction of the light is caused by dust molecules forming dense clouds.

Dark nebulas are generally coated with frozen carbon monoxide and nitrogen, which effectively block the passage of light at visible wavelengths. Also present are molecular hydrogen, atomic helium, C¹⁸O (CO with oxygen as the ¹⁸O isotope), CS, NH₃ (ammonia), H₂CO (formaldehyde), c-C₃H₂ (cyclopropenylidene) and a molecular ion N₂H⁺ (diazenylium), all of which are relatively transparent. Due to presence of these gases these giant clouds are so dense and opaque.

       

The form of such dark clouds is very irregular: they have no clearly defined outer boundaries sometimes take on convoluted serpentine shapes.Some of these dark nebulas are..Coalsack Nebula, Cone Nebula, Dark Doodad Nebula, Dark Horse Nebula, Horsehead Nebula, Pipe Nebula, Snake Nebula. The largest dark nebulae are visible to the naked eye, appearing as dark patches against the brighter background of the Milky Way like the Coalsack Nebula and the Great Rift.