# Milky Way primordial galactic merger discovery

> Live situation record from CLSTR: https://clstr.news/situations/milky-way-primordial-galactic-merger-discovery
> Updated: 2026-08-24T05:30:44.000Z. Sources: 45. Developments: 4.

Astrophysicists have identified evidence of a primordial galactic merger within the inner regions of the Milky Way. Using data from the Hubble Space Telescope, the Euclid space telescope, and ESA’s Gaia mission, researchers conducted cosmic archaeology by analyzing the age, chemical composition, and trajectories of globular clusters.

The study, published in Nature Astronomy and led by Davide Massari, indicates this merger occurred approximately 11.8 billion years ago, roughly 2 billion years after the Big Bang. This event predates the previously documented Gaia-Enceladus impact by about 1.8 billion years. The absorbed dwarf galaxy, named Low-energy-Kraken-Heracles (LKH), possessed a stellar mass equivalent to roughly 500 million suns, representing approximately a quarter of the Milky Way’s total mass at that time.

Newer research from the National Institute for Astrophysics (Inaf) as part of the Carma project suggests these findings address a period of uncertainty in galactic history, showing that foundational building blocks were incorporated much earlier than previously understood. Scientists have noted that stars in the peripheral regions of globular clusters preserve traces of these earliest interactions.

In related developments regarding galactic structure, research published in ‘Astronomy and Astrophysics’ has utilized data from the Gaia satellite, the Lamost telescope, and the Apogee spectrograph to define the galaxy's physical limits. By analyzing over 100,000 celestial bodies, researchers estimated the distance to the galactic edge to be between 11.28 and 12.15 kiloparsecs, suggesting a total galactic diameter of up to approximately 100,000 light-years.

## Claims

- The Milky Way swallowed a dwarf galaxy approximately 11.8 billion years ago. (corroborated by 3 sources)
- The absorbed dwarf galaxy is named Low-energy-Kraken-Heracles (LKH). (corroborated by 3 sources)
- Astronomers used the Hubble and Gaia telescopes to study stellar clusters within the inner 20,000 light-years of the Milky Way. (corroborated by 3 sources)
- The discovery represents the Milky Way's earliest-known galactic merger. (corroborated by 2 sources)
- The LKH galaxy had a stellar mass equivalent to 500 million suns at the time of the merger. (corroborated by 2 sources)
- The merger occurred roughly 2 billion years after the Big Bang. (corroborated by 2 sources)
- The Gaia-Sausage-Enceladus collision, which occurred about 10 billion years ago, was previously considered the oldest major impact. (corroborated by 2 sources)
- A collision with the Sagittarius dwarf galaxy began approximately 6 billion years ago and continues today. (corroborated by 2 sources)

## Timeline

### 2026-08-24: Milky Way research reveals ancient galaxy mergers and boundaries

Astronomers are uncovering the Milky Way's origins and boundaries, identifying an ancient galaxy merger and estimating the galaxy's diameter to be up to 100,000 light-years.

2 sources. https://clstr.news/cluster/milky-way-research-reveals-ancient-galaxy-mergers-and-boundaries

### 2026-08-22: Milky Way absorbed a massive galaxy 11.8 billion years ago

Astronomers have identified a massive galactic merger involving the Milky Way and the dwarf galaxy Low-energy-Kraken-Heracles that occurred 11.8 billion years ago, reshaping our understanding of galactic growth

6 sources. https://clstr.news/cluster/milky-way-history-rewritten-by-discovery-of-ancient-galactic-merger

### 2026-08-17: Milky Way merger discovered 11.8 billion years ago

Astronomers using the Hubble Space Telescope have identified an ancient merger between the Milky Way and the dwarf galaxy Low-energy-Kraken-Heracles (LKH) that occurred 11.8 billion years ago.

30 sources. https://clstr.news/cluster/hubble-telescope-reveals-milky-ways-oldest-galactic-merger

### 2026-08-17: Astrophysicists identify primordial Milky Way merger and study star formation

Astrophysicists have discovered evidence of a Milky Way galactic merger occurring two billion years after the Big Bang, while new radio astronomy studies are mapping the chemical conditions of star formation in

7 sources. https://clstr.news/cluster/astrophysicists-identify-primordial-milky-way-merger-and-study-star-formation

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Cite as: Milky Way primordial galactic merger discovery. CLSTR, https://clstr.news/situations/milky-way-primordial-galactic-merger-discovery