The stars that lit up the early Milky Way

Imagine trying to reconstruct the history of a city by studying only its oldest surviving buildings. You can't watch it being built, you can't interview the architects, all you have are the structures themselves, their materials, their arrangement, the subtle clues locked into their very fabric. That is essentially what astronomers do when they study the formation of our galaxy, and a new study has just given them their biggest collection of clues yet.