Using a giant radio telescope in southeastern Australia, the researchers have identified the galactic clouds of molecular gas -- some up to 100 light-years across -- from the carbon monoxide they contain.
"On Earth, carbon monoxide is poisonous -- a silent killer. But in space, it is the second most abundant molecule and the easiest to see," project leader Michael Burton of the University of New South Wales said.
The carbon monoxide survey of the Southern Milky Way is being carried out with a 72-foot radio telescope in Coonabarabran.
"One of the largest unresolved mysteries in galactic astronomy is how these giant, diffuse clouds form in the interstellar medium," Burton said. "This process plays a key role in the cosmic cycle of birth and death of stars."
The project is part of an international effort also searching for "dark" galactic gas clouds, unseen clouds that contain very little carbon monoxide.
It is assumed these clouds are mostly made up of molecular hydrogen too cold to detect, and astronomers are using telescopes in Antarctica and Chile to search for these dark clouds based on the presence of carbon atoms rather than carbon molecules.
"Taken together, these three surveys will provide us with a picture of the distribution and movement of gas clouds in our galaxy," Burton said.