Amina Helmi, a 55-year-old astronomer at the University of Groningen, has won the Kavli Prize for her leading work in galactic archaeology. Using ESA's Gaia mission data — about 1.5 billion stellar motions — Helmi helped reconstruct a major ancient merger with the dwarf galaxy Gaia-Enceladus around 10 billion years ago. Her findings show the Milky Way formed through successive mergers rather than smooth growth; she plans to continue refining models and analysing future Gaia releases.
“Cosmic Fossils”: Amina Helmi Wins Kavli Prize for Revealing the Milky Way’s Violent Past
The Milky Way had a turbulent birth (-)
Amina Helmi's passion for the Milky Way is evident the moment you step into her modest office at the University of Groningen in the Netherlands. Between family photographs and stacks of dense dissertations sits a bowl of chocolates stamped with the name of the star system she has spent her career studying.
The 55-year-old Argentine-born astronomer has been awarded the prestigious Kavli Prize for her pioneering contributions to galactic archaeology — a field that treats stars as "cosmic fossils" to reconstruct the history and evolution of our galaxy.
Rather than peering through a telescope, Helmi spends her days mining vast catalogues of stellar data. "We can measure, for example, the amount of chemicals in the stars," she told AFP, explaining that elemental abundances act like a star's DNA, preserving clues about where and how a star was born.
A turning point for Helmi's work was the European Space Agency's Gaia mission. Gaia has measured the positions and motions of roughly 1.5 billion stars, delivering unprecedented precision and volume of data. Helmi, a contributor to the mission, used those measurements to trace the Milky Way's formative collisions.
'Speechless'
Using Gaia's data, Helmi and collaborators reconstructed a defining event in the Milky Way's history: about 10 billion years ago a dwarf galaxy now called Gaia-Enceladus merged with the proto-Milky Way. The collision deposited many stars into a surrounding halo, triggered bursts of star formation, and produced the Milky Way's thicker, "puffed-up" stellar disc.
These discoveries overturned the older view of smooth, gradual growth and showed that our galaxy assembled through hierarchical mergers — a finding that Helmi shares the Kavli Prize for, alongside Vasily Belokurov (University of Cambridge) and Rodrigo Ibata (University of Strasbourg).
Helmi will receive part of the $1 million prize fund, a medal and citation at a ceremony in Oslo organised by the Norwegian Academy of Science and Letters. The award citation recognised the trio for "uncovering the fossil evidence of past mergers proving that the Milky Way galaxy was built through hierarchical accretion."
"To me, this is indeed the biggest there is. And it's just absolutely unbelievable," Helmi said, admitting she was "totally speechless" at the news.
Looking ahead, Helmi plans to analyse further Gaia data releases and to develop new modelling techniques to extract more information from ever-larger datasets. Asked what the Milky Way's tumultuous youth implies for its future, she smiled: "Nothing much has happened since then. So you could say it's been a wild youth and now a quiet, restful adulthood."
Why this matters: Helmi's work shows how modern astronomical surveys and careful data analysis can turn millions or billions of measurements into a clear narrative of galactic evolution, revealing our galaxy's past collisions and shaping how astronomers understand galaxy formation more broadly.
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