The Giant Molecular Cloud in Orion

The white lines in the photo at left outline the well-known constellation of Orion the Hunter. The slightly pinkish blob in the Hunter's sword is the Orion Nebula, the nearest and most well-studied region of massive star formation in our Galaxy. Flashing on and off is a false-color map of the distribution of dense molecular gas in Orion, obtained with our northern 1.2 meter telescope over the course of several years.

Prior to ~1970, molecules were thought be quite rare in interstellar space, because the chemical bond that holds molecules together is so fragile. When our telescope was first switched on in 1974, it was immediately aimed at the Orion nebula. It was not surprising to find some molecular gas in the vicinity of young stars--since stars form out of dense gas--but what was surprising was the great extent and mass of the gas.

Note how the Orion Nebula lies in the densest part of a so-called giant molecular cloud. This cloud is about 1,500 light years away and contains enough gas to make 200,000 Suns.