Artist's illustration of two galaxies colliding in deep space, with a bright elongated galaxy and a smaller luminous mass merging against a star-filled cosmic backdrop.
via REUTERS/NASA, ESA, Joseph Olmsted (STScI

The Milky Way Devoured a Smaller Galaxy 11.8 Billion Years Ago, and Some of Its Stars Are Still Hiding Inside Us

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Long before there was a sun, an Earth, or a you, a smaller galaxy fell into ours and dissolved. Some of the stars it carried never left, and the collision that swallowed them helped set in motion everything that eventually became your life.

Roughly 11.8 billion years ago, when the universe was less than 15% of its current age, a dwarf galaxy called Low-energy-Kraken-Heracles slipped into the Milky Way’s gravity and never came back out. It’s the earliest merger our galaxy has ever left a trace of, and it means the place you call home was assembled from pieces of somewhere else.

Artist's concept of a dwarf galaxy colliding and merging with the Milky Way, showing swirling gas, dust lanes, and bright stellar clusters against a star-filled background.
An artist’s concept depicts the ancient merger of the dwarf galaxy LKH with the Milky Way approximately 11.8 billion years ago, released August 17, 2026. Photo by NASA, ESA, Joseph Olmsted (STScI) via REUTERS.

That smaller galaxy carried stars weighing as much as 500 million suns, about a quarter of what the Milky Way held at the time. For the stars, the collision was gentle, no crashes, just an absorption. For the gas the two galaxies were made of, it was violent enough to ignite whole generations of new stars.

Night sky over palm trees at Fellsmere Grade Recreation Area showing the Milky Way, wispy clouds, and a green meteor streak.
A meteor streaks a green line across the star-filled sky above palm trees at the Fellsmere Grade Recreation Area on Aug. 12, 2026, with the Milky Way visible through scattered clouds. Photo via USA TODAY Network / Reuters Connect.

Some of those ancient stars are still down there, buried near the center of the galaxy under so much interstellar dust that they’re almost impossible to pick out one by one. You can’t see them. They’re part of the same story you are.

Every merger like this one nudged the conditions that would eventually produce a sun, a planet, and the specific chemistry of you. The question underneath all of it is the oldest one you know how to ask: where do we come from?