{
  "id": 16508311,
  "title": "Milky Way's disk grew 'upside down,' with younger stars forming in ever-thinner layers",
  "url": "https://urgent.news/2026/10/25/milky-ways-disk-grew-upside-down-with-younger-stars-forming-in-ever",
  "topic": "science",
  "section": "Science",
  "published": "2026-10-25T18:30:02.000Z",
  "source": {
    "name": "Phys.org",
    "slug": "phys-org",
    "url": "https://phys.org/news/2026-10-milky-disk-grew-upside-younger.html"
  },
  "original_language": "en",
  "account": "The Milky Way's galactic disk has grown from the inside out, beginning with a thick disk and giving rise to a thin disk over time, as revealed by new research. Astronomers have long struggled to understand the formation of this disk and the Milky Way as a whole. Observations have suggested multiple explanations, such as star birth in the thin disk followed by perturbations, or the gas from which stars form settling into an even thinner disk with each successive generation. However, accurately measuring the ages of individual stars has proven challenging, especially for the oldest ones.\n\nA recent study in The Astrophysical Journal Letters, led by David Mirabal, used data from Gaia Data Release 3 to tackle this issue. The research reveals two distinct phases in the formation of the Milky Way's disk, explaining its vertical structure. Before about 10.8 billion years ago, the disk flattened rapidly, with stars born in the thick disk due to a more turbulent and puffed-up early universe. About 10.8 billion years ago, a significant change occurred as the thin disk formed, and the older stars retained their orbits in the thick disk. The thin disk, which holds younger stars and most of the Milky Way's gas and dust, is the site of most star formation. The researchers' findings support an evolutionary scenario characterized by two distinct temporal phases: an initial, highly turbulent epoch that gave birth to the thick disk, followed by a more quiescent period of secular evolution and gradual gas settling, which formed the thin disk.",
  "summary": "The Milky Way is home to hundreds of billions of stars arranged in a glorious spiral pattern. But beyond the obvious spiral, our galaxy has other physical characteristics. It's divided into a galactic bulge, a galactic disk and a galactic halo.",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}