NASA's Hubble Space Telescope found definitive evidence of a dwarf galaxy merging with the young Milky Way 11.8 billion years ago, just two billion years after the big bang.
Image credit: NASAThis breakthrough extends our understanding of the Milky Way’s growth by 1.8 billion years. It demonstrates that our home galaxy built its mass far earlier than previously confirmed.
Image credit: NASAOur galaxy grew by absorbing others. Recent examples include the ongoing Sagittarius merger and the massive Gaia-Sausage-Enceladus merger that restructured the stellar disk ten billion years ago.
Image credit: NASAAstronomers used Hubble to analyze 39 globular clusters within the inner 20,000 light-years of our galaxy. These dense stellar groups serve as cosmic archaeological sites.
Image credit: NASABy measuring cluster ages and chemical compositions, researchers combined Hubble depth with Gaia spacecraft data to isolate stars born outside our early galactic boundary.
Image credit: NASAData revealed a distinct third population of globular clusters from an ancient dwarf galaxy named LKH, which brought roughly 500 million solar masses of stars into our galaxy.
Image credit: NASAPrevailing theories held that only internal stars formed the galaxy's earliest structure. The discovery proves that absorbed external galaxies played a crucial structural role from the start.
Image credit: NASAResearchers plan to examine previously unstudied globular clusters with Hubble. Their goal is to fully map every major galactic merger across the entire history of the Milky Way.
Image credit: NASAContinue with another visual space report selected from our latest published Stories.
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