An infrared dark cloud (IRDC) is a cold, dense region of a giant molecular cloud). They can be seen in silhouette

Silhouette

A silhouette is the image of a person, an object or scene consisting of the outline and a basically featureless interior, with the silhouetted object usually being black. Although the art form has been popular since the mid-18th century, the term “silhouette” was seldom used until the early decades...

 against the bright diffuse mid-infrared emission from Galactic plane

Galactic plane

The galactic plane is the plane in which the majority of a disk-shaped galaxy's mass lies. The directions perpendicular to the galactic plane point to the galactic poles...

.

Discovery

Infrared dark clouds have only been recently discovered in 1996 using the ISO

Infrared Space Observatory

The Infrared Space Observatory was a space telescope for infrared light designed and operated by the European Space Agency , in cooperation with ISAS and NASA...

  and therefore are in need of further research.

Importance

Astronomer

Astronomer

An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...

s believe that they represent the earliest stage in the formation of high-mass stars
and are therefore of great importance for understanding the star formation process as a whole.