Galactic Archaeology

Astronomers practice galactic archaeology — studying the chemical compositions and orbits of stars to reconstruct the Milky Way's history. Stars that formed together share the same chemical fingerprint, allowing scientists to identify ancient stellar families scattered across the galaxy over billions of years.

The ESA's Gaia mission has mapped the positions and motions of nearly 2 billion stars with unprecedented precision. This data has revealed that the Milky Way experienced a major merger roughly 10 billion years ago with a galaxy now called Gaia-Enceladus.