New data from the NASA/ESA Hubble Space Telescope show evidence of a dwarf galaxy merging with the young Milky Way in the earliest phases of its evolution, ESA reported on 17 August 2026. According to the findings, the event extends knowledge of the galaxy's history 1.8 billion years farther back than before.

Researchers analysed Hubble observations of 39 globular clusters in the inner 20 000 light-years of the Milky Way, using Gaia measurements alongside them. They identified a third population of clusters, older than those linked to the Gaia-Sausage-Enceladus merger about 10 billion years ago but younger than those born in the Milky Way. The team says these clusters came from a separate, earlier merger roughly 11.8 billion years ago, in which the Milky Way absorbed a dwarf galaxy holding about 500 million times the Sun's mass in stars. They named it Low-energy-Kraken-Heracles, or LKH.

The team plans to keep studying globular clusters to characterise the massive mergers in the galaxy's history.