Free Astronomy Magazine July-August 2026

38 JULY-AUGUST 2026 ASTRO PUBLISHING Nature Astronomy , show that it is the most massive star clusters that clear away their gaseous shroud the fastest, and begin lighting their galaxy the earliest. The team identified nearly 9,000 star clusters in the four galaxies in different evolutionary stages: young clusters just starting to emerge from their natal clouds of gas, clusters that had partially dispersed the gas (both from Webb images), and fully unob- structed clusters visible in optical light (found in Hubble images). With Webb’s ability to peer inside the gas clouds, they were able to then estimate the mass and age of each cluster from its light spectrum. The most massive clusters had fully emerged and dispersed the clouds of gas after around five million years, while less massive clusters were between seven and eight million years old when they emerged from their nurseries. T his image shows the four galaxies studied in this research, each of which has pre- viously been the sub- ject of an ESA/Webb Picture of the Month: from top to bottom, M51, NGC 4449, M83 and NGC 628. [ESA/Webb, NASA & CSA, A. Pedrini, A. Adamo (Stockholm University) and the FEAST JWST team]