Dark nebula

The extinction of the light is caused by interstellar dust grains in the coldest, densest parts of molecular clouds.

Clusters and large complexes of dark nebulae are associated with Giant Molecular Clouds.

Dark clouds appear so because of sub-micrometre-sized dust particles, coated with frozen carbon monoxide and nitrogen, which effectively block the passage of light at visible wavelengths.

[1][2] The form of such dark clouds is very irregular: they have no clearly defined outer boundaries and sometimes take on convoluted serpentine shapes.

In the inner molecular regions of dark nebulae, important events take place, such as the formation of stars and masers.

The dark nebula LDN 1768 in front of background stars
The Milky Way as seen by Gaia, with prominent dark features labeled in white, as well as prominent star clouds labeled in black.
Main dark nebulae of the solar apex half of the galactic plane .
Main dark nebulae of the solar antapex half of the galactic plane.