This Is How Old Our Galaxy Really Is: Milky Way Birthday Discovered

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The Milky Way galaxy is no spring chicken.

Scientists have finally determined the age of our home galaxy, saying its origins date back to just 800 million years after the Big Bang occurred.

The most established cosmic dust settled at the center of our galaxy about 13 billion years ago, researchers concluded, while the outer edge of its pinwheel arms was borne out of a collision with the Gaia-Enceladus galaxy, a dwarf galaxy that merged with the Milky Way between 8 and 11 billion years ago.

The findings were published in the journal Nature on Wednesday, compiled by astronomers Maosheng Xiang and Hans-Walter Rix of the Max-Planck Institute for Astronomy. They analyzed a survey of nearly a quarter-million stars — ranging in age from 13.8 billion to 15 billion years old — to track our galaxy’s growth by cross-referencing their lifecycles with the Milky Way’s movements.

Xiang and Rix set their telescopic sights onto low-mass stars — like our sun — during their midlife, or “sub-giant” phase, at which point the glow ignited by their ballooning hydrogen allows us to more easily observe and estimate their projected life cycle.

“With an innovative approach to estimating the birth dates of stars, Xiang and Rix have succeeded in helping us to better understand how our galaxy formed,” said University of Notre Dame physicist Timothy Beers in an editorial tied to the new report.

“And the approach is scalable, which means that, as data for larger samples of stars in the Milky Way become available, this picture will come into even sharper focus,” he said.