Hubble captures 500,000‑star globular cluster Messier 3

NASA marked the United States’ 250th anniversary by unveiling a new Hubble Space Telescope portrait of Messier 3, a globular cluster located roughly 34,000 light‑years from Earth. The image captures the dense core of the ancient stellar assembly, which contains more than half a million stars packed into a region only about 200 light‑years across. Messier 3’s age, estimated at around 11 billion years, makes it one of the Milky Way’s oldest surviving structures, and its vivid depiction highlights the capabilities of Hubble’s instruments in resolving individual stars within such crowded environments.

Astronomers are using the cluster’s rare stellar populations to probe the formation history of the Milky Way. Certain stars in Messier 3 exhibit chemical signatures that suggest they originated in a dwarf galaxy that merged with the Milky Way early in its evolution, offering clues to past cosmic collisions. By analyzing these stars’ motions and compositions, researchers hope to refine models of the galaxy’s assembly and better understand the role of ancient mergers in shaping its present structure. The release of the portrait underscores both the scientific value of the cluster and the continued relevance of Hubble’s observations in galactic archaeology.