Molecular Cloud
A dense and cold region of interstellar space composed primarily of molecular hydrogen, serving as the birthplace of stars. The molecular cloud associated with NGC 346 is actively forming new stars.
Source: science.nasa.gov
APODs including "Molecular Cloud"
Star Clouds Toward the Southern Crown
02/10/2002
The flowing trails of dust toward Corona Australis, the constellation of the Southern Crown, are visible here not because they glow, but because they absorb and reflect. The dust appears bluer when seen near bright stars because it preferentially reflects blue light. The densest knots of dust are so thick that no background stars or interior stars can be seen through them. These knots indicate molecular clouds filled with cool gas where future stars will likely form. The above image spans about 5 degrees while the reflection nebula lies about 500 light-years distant.