Archaeologists and astronomers don’t seem to have much in common. One digs into the earth while the other looks at the sky, and a stone tool once wielded by Homo erectus couldn’t be more different from an exploding star at the edge of the visible universe. But the sciences are actually fundamentally similar: Both try to understand the present by looking deep into the past, whether it’s the origin of the human species or of the universe.
For some astronomers, the parallels are even closer. One of the great mysteries of the cosmos is how and when and why the first stars flared into light out of the darkness that followed the Big Bang. Nobody knows for sure what those first stars looked like, or how they lived and died. But their emergence set the stage for everything that followed — all of the planets, stars and galaxies that light up the night sky. Understand the first stars, and you understand how the universe took shape.
The gulf in time and space is so great that even the most powerful telescopes can’t see the faint light from those first stars. But in recent years, a new breed of astronomers — stellar archaeologists — has realized there’s a way to understand them by looking close to home, within and around the Milky Way. By examining the chemistry of the oldest nearby stars, they’re beginning to understand the conditions in which those stars formed, conditions created in part by the short-lived and massive first generation of stars that came before. “We can still see their environmental impact, the pollution that these massive stars introduced,” says Avi Loeb, head of the astronomy department at Harvard.
The good news is that second-generation stars are all around us. “Some of the best examples we have are just a few hundred light-years from us,” says Timothy Beers, the provost’s chair of astrophysics at Notre Dame. “They’re really not that far away, and it tends to surprise people that we can understand the distant past by looking so close to home.”
