Our Sun appears to have been part of a large-scale stellar migration—alongside numerous ‘solar twins’—that originated in the central regions of the Milky Way roughly four to six billion years ago. This conclusion comes from a study by astronomers who analyzed data from the European Space Agency’s Gaia satellite, which is mapping over two billion stars and other celestial objects with unprecedented precision.
A Broader Family Portrait
Researchers from Tokyo Metropolitan University and Japan’s National Astronomical Observatory conducted a comprehensive survey of stars with physical properties closely matching those of the Sun—similar temperature, surface gravity, and chemical composition. Using Gaia’s high-accuracy measurements, they identified 6,594 solar twin candidates—a catalog nearly 30 times larger than any previous effort. This allowed them to determine stellar ages with greater accuracy than ever before.
A Shared Cosmic History
The team found a broad population of stars aged approximately 4–6 billion years—including our Sun—all located at roughly the same distance from the galactic center. That alignment suggests the Sun did not end up where it is today by chance. Instead, it likely formed closer to the Milky Way’s core—within about 20,000 light-years—and later migrated outward to its current position some 27,000 light-years from the center.
Clues to Galactic Evolution
This discovery sheds new light on how our galaxy evolved—particularly on the formation of its central bar-like structure. Such a dense, rotating bar would normally act as a barrier to large-scale stellar movement. Yet the observed migration implies the bar may not have fully formed at the time of the Sun’s birth—or may have taken shape gradually over the same timeframe. In other words, the ages of these solar twins not only pinpoint when the migration occurred but also help constrain when the galactic bar itself assembled.
What Lies Ahead
The research team plans to use increasingly precise observations of Sun-like stars to reconstruct the Sun’s original birthplace and trace the full path of this ancient stellar exodus.