ESA Science & Technology - Mapping Invisible Pools of Gas in Our Galaxy (Illustration)

This illustration shows a newfound reservoir of stellar fuel discovered by the Herschel space observatory (red). Stars are formed out of pools of gaseous hydrogen molecules. To locate these pools, astronomers have historically looked for carbon monoxide (CO), which is co-located with the hydrogen gas (orange). But this tracer molecule does not lead astronomers to all of the star-making material in our galaxy. By using Herschel to map ionized carbon (C⁺), scientists were able to find additional reservoirs of the hydrogen gas.

Originally published at the NASA JPL website.