What is Molecular cloud?
[[File:Young_Stars_in_the_Rho_Ophiuchi_Cloud.jpg|thumb|Young stars surrounded by a giant molecular cloud in the [[Ophiuchus]] constellation]] A '''molecular cloud''' is a kind of [[Nebula|cloud in space]]. It has enough [[density]] and size so that [[molecule]]s can form, usually molecules of hydrogen (H<sub>2</sub>). Molecular hydrogen is not easy to find. Instead [[astronomer]]s use [[infrared]] telescopes and [[radio telescope]]s to look for CO ([[carbon monoxide]]). This lets them find the hydrogen molecules that are also there. {{science-stub}} [[Category:Nebulae|Molecular cloud]]