Cloud L1688 is like a dance floor where partners don't always hold hands. Astronomers assumed that gas in star-forming clouds moves along with the stars. But testing this was difficult: only the gas's velocity along the line of sight was measured, while its sideways motion across the sky remained invisible.

Now, images of the same region taken by the Hubble telescope in 2016 and the James Webb telescope in 2023 were compared. Over 6.5 years, the gas had shifted slightly. To measure this shift, the images were aligned using distant galaxies, and a computer program was used to find how much the gas patterns had moved. It turned out that the gas moves differently from the young stars: the difference in velocity is about 3 km/s. This means that stars cannot always serve as accurate tracers of gas motion.

Now astronomers have a way to track the dance of the cloud and the stars separately. This will help better understand how stars form and how they influence their surroundings.