Milky Way's disk grew 'upside down,' with younger stars in ever-thinner layers

Astronomers found that the Milky Way's disk grew 'upside down': younger stars formed in ever-thinner layers, reshaping the galaxy's structure. The Milky Way consists of a galactic bulge, disk and halo.

• The Milky Way's disk grew 'upside down' rather than bottom-up
• Younger stars formed in progressively thinner layers of the disk
• The galaxy comprises a bulge, a disk and a halo