Hubble data point to M30's possible capture by the Milky Way

NASA said Hubble observations suggest M30 may have been captured by the Milky Way. The agency published the announcement Thursday 05 November 2026. The cluster lies about 27,500 light-years away in Capricornus and contains tens of thousands to millions of stars.

M30 is a globular cluster, or a roughly spherical grouping of stars. These clusters generally orbit in the outskirts of galaxies. The Milky Way has at least 150 globular clusters, and its nearest is about 6,000 light-years away.

Astronomers estimate that globular clusters are between 11.5 to 13.5 billion years old. Their ancient stars can reveal how the Milky Way developed long ago and preserve the original chemistry of the young galaxy. M30 and many other clusters orbit opposite the direction of the galaxy's spin. NASA said this may mean they formed elsewhere and were captured in the distant past.

Hubble has observed M30 multiple times. A program with the Advanced Camera for Surveys surveyed dozens of Milky Way globular clusters in red and near-infrared light. It revealed stars down to just 20% of the mass of the Sun. A more recent program used the Wide Field Camera 3 and three filters to capture bluer light. The data aided research on blue straggler stars and the multiple populations of stars within globular clusters.

Hubble's Advanced Camera for Surveys later observed many globular clusters again. The program examined how different star populations moved over the 15 years since Hubble first observed them. The new image combines data from all three observing programs and covers ultraviolet, visible and near-infrared light.

NASA said each wavelength helps astronomers understand how groups of stars form and evolve. Claire Andreoli of NASA's Goddard Space Flight Center wrote the announcement. It said Hubble has changed astronomers' fundamental understanding of the universe since its 1990 launch.