Timothy C. Beers

At the edge of the Milky Way, there are stars that move against the general flow, like cars driving in the wrong lane. Previously, it was thought that all of them were remnants of one dwarf galaxy that our Galaxy tore apart and swallowed. But new research shows that there were several such 'oncoming' galaxies.

An archaeologist holds in their hands not a clay shard but an actual star — a living snapshot of the era when the universe was just learning to produce anything heavier than lithium. That is exactly the kind of find astronomers describe in a new study. They spotted four dim stars so ancient and pristine in composition that their matter is barely diluted by the 'cosmic dust' of later generations.