Question

Why do molecules, including H2 and more complex organic molecules, only form inside dark clouds? Why don’t they fill all interstellar space?

Answer 1

Step-by-step explanation:

A molecular cloud also called a stellar nursery , is a type of the interstellar cloud, with the composition of commonly the molecular hydrogen ,

In dark clouds , the accumulation of the dust in a specific location , which blocks the starlight and hence , stopping ionization , and thereby making that area dark .

They do not fill all of the intersteller space , because , the number of dust grains only account for a fraction of the volume of the intersteller space .