Stars dont form out of nothing, but tracking the gas and dust that do eventually form stars is hard. They float around the galaxy at almost absolute zero, emitting essentially no light, and generally making life difficult for astronomers. But, part of how they make life difficult is actually the key to studying them - they have absorption lines that detail what kind of material the light is passing through on its way to Earth. A new paper from Harvey Liszt of Americas National Radio Astronomy Observatory and Maryvonne Gerin of the Sorbonne details how tracking those absorption lines via radio astronomy can trace the dark neutral medium of interstellar gas throughout the galaxy.