Molecular cloud
A molecular cloud is a kind of cloud in space. It has enough density and size so that molecules can form, usually molecules of hydrogen (H2). Molecular hydrogen is not easy to find. Instead astronomers use infrared telescopes and radio telescopes to look for CO (carbon monoxide). This lets them find the hydrogen molecules that are also there.
Molecular Cloud Media
Astronomer Henk van de Hulst first theorized hydrogen could be traceable in interstellar space using radio signals.
Jansky and his rotating directional radio antenna (early 1930s), the world's first radio telescope.
Plaque commemorating the discovery of 21-cm radiation from the Milky Way
Left to right: Jan Oort, Hendrik C. van de Hulst, Pieter Oosterhoff. Jan Oort had a pivotal role in the research that lead to the discovery of molecular clouds.
Penzias and Wilson with the Holmdel horn antenna used to detect microwave emissions from the Big Bang
Molecular cloud Barnard 68, about 500 ly distant and 0.5 ly in diameter
Circinus molecular cloud has a mass around 250,000 times that of the Sun.
The star T Tauri with NGC 1555 cloud nearby.
The Elephant's Trunk Nebula is an elongated dark globule. The globule is a condensation of dense gas that is barely surviving the strong ionizing radiation from a nearby massive star.
Taurus Molecular Cloud. Located about 430 light-years from us, this vast complex of interstellar clouds is where a large amount of stars are being born, and is the closest large region of star formation.
