A molecular cloud, sometimes called a stellar nursery if star formation is occurring within, is a type of interstellar cloud whose density and size permits the formation of molecules, most commonly molecular hydrogen (H2).
Molecular hydrogen is difficult to detect by infrared and radio observations, so the molecule most often used to determine the presence of H2 is CO (carbon monoxide). The ratio between CO luminosity and H2 mass is thought to be constant, although there are reasons to doubt this assumption in observations of some other galaxies.
Read more about Molecular Cloud: Occurrence
Famous quotes containing the word cloud:
“Misfortune is never mournful to the soul that accepts it; for such do always see that every cloud is an angel’s face. Every man deems that he has precisely the trials and temptations which are the hardest of all others for him to bear; but they are so, simply because they are the very ones he most needs.”
—Lydia M. Child (1802–1880)