This image from the MPG/ESO 2.2-meter telescope at ESO's La Silla Observatory in Chile shows NGC 6388, a dynamically middle-aged globular cluster in the Milky Way. While the cluster formed in the distant past (like all globular clusters, it is over ten billion years old), a study of the distribution of bright blue stars within the cluster shows that it has aged at a moderate speed, and its heaviest stars are in the process of migrating to the center. A new study using ESO data has discovered that globular clusters of the same age can have dramatically different distributions of blue straggler stars within them, suggesting that clusters can age at substantially different rates. Credit: ESO, F. Ferraro (University of Bologna)

Some people are in great shape at the age of 90, while others are decrepit before they're 50. We know that how fast people age is only loosely linked to how old they actually are—and may have more to do with their lifestyle. A new study using both the MPG/ESO 2.2-metre telescope at ESO's La Silla Observatory and the NASA/ESA Hubble Space Telescope reveals that the same is true of star clusters.